Chemical amplifying type positive resist composition and sulfonium salt

ABSTRACT

A chemical amplifying type positive resist composition which provides a resist pattern having an exceedingly improved line edge roughness, and is excellent in various resist performances such as dry etching resistance, sensitivity and resolution; and comprises:  
     (A) an acid generator containing (a) a sulfonium salt represented by the following formula (I):  
                 
 
     wherein Q 1  and Q 2  is alkyl or a cycloalkyl, or Q 1  and Q 2  form, together with a sulfur atom to which Q 1  and Q 2  are adjacent, an heteroalicyclic group; Q 3  represents a hydrogen atom, Q 4  represents alkyl or a cycloalkyl, or Q 3  and Q4 form, together with a CHC(O) group to which Q 3  and Q4 are adjacent, a 2-oxocycloalkyl group; and Q 5 SO 3   −  represents an organosulfonate ion, and  
     (b) at least one onium salt selected from a triphenylsulfonium salt represented by the following formula (IIa), and a diphenyliodonium salt represented by the following formula (IIb);  
                 
 
     wherein P 1  to P 5  represent hydrogen, a hydroxyl group, alkyl, or alkoxy; and P 6 SO 3   −  and P 7 SO 3   −  each independently represent an organosulfonate ion; and  
     (B) a resin which has a polymerization unit having a group instable against an acid, and is alkali-insoluble or -slightly soluble itself, but is converted to alkali-soluble by the action of an acid.

FIELD OF THE INVENTION

[0001] The present invention relates to a chemical amplifying typepositive resist composition for use in the fine processing of asemiconductor.

[0002] In general, a lithography process using a resist composition isadopted for the fine processing of a semiconductor, In lithography, theshorter the exposure light wavelength is, the more the resolution can behigher in principle, as shown by Rayleigh's formula for diffractionlimited. Exposure light sources for lithography used for manufacturing asemiconductor, such as a g-line with a wavelength of 436 nm, an i-linewith a wavelength of 365 nm, a KrF excimer laser with a wavelength of248 nm, and an ArE excimer laser with a wavelength of 193 nm have beenadopted. Thus, the wavelength thereof has been reduced year by year. AF2 excimer laser with a wavelength of 157 nm is regarded as beingpromising as the next-generation exposure light source. Thereafter, asoft X-ray (EUV) with a wavelength of not more than 13 nm is proposed asa light source.

[0003] Since a light source having a shorter wavelength than that of ag-line or an i-line, such as an excimer laser, has low illuminationintensity, the sensitivity of a resist is required to be increased. Forthis reason, there is used a so-called chemical amplifying type resistcontaining a resin having a group utilizing the catalytic action of anacid which is generated through light exposure, and is cleaved by theacid.

[0004] However, with a chemical amplifying type resist composition knownin the art, the line edge roughness, i.e., the smoothness of the patternside wall is deteriorated due to the occurrence of a standing wave, orthe like. As a result, there occurs a problem that the uniformity of theline width is deteriorated.

[0005] An object of the present invention is to provide a chemicalamplifying type positive resist composition which comprises a resincomponent and an acid generator; is suitable for excimer laserlithography using an ArF excimer laser, a KrF excimer laser, or thelike; is excellent in various resist performances such as sensitivityand resolution; and provides a particularly improved line edgeroughness.

[0006] The present inventors have already found and proposed thefollowing fact. Namely, by using at least one onium salt selected fromtriphenylsulfonium salt and diphenyliodonium salt, and aperfluoroalkylsulfonate salt of 2-oxosulfonium such ascyclohexylmethyl(2-oxosulfonium)perfluoroalkyl sulfonate in combinationas an acid generator, the resolution is improved, and the profile on abasic substrate or a low reflectance substrate is also improved(Japanese Patent Application No.2000-060057). Thereafter, they havefound that this combination system is also capable of improving the lineedge roughness, and further conducted a study thereon. As a result, theyhave found that by using a specific sulfonium salt in place of theperfluoroalkylsulfonate salt of 2-oxosulfonium in the combination, it ispossible to improve the line edge roughness. Thus, they have completedthe present invention.

SUMMARY OF THE INVENTION

[0007] The present invention provides a practically excellent chemicalamplifying type positive resist composition which comprises:

[0008] (A) an acid generator containing (a) a sulfonium salt representedby the following formula (I);

[0009] wherein Q¹ and Q² each independently represent a straight chainor branched alkyl group having from 1 to 6 carbon atoms or a cycloalkylgroup having from 3 to 10 carbon atoms, or Q¹ and Q² form, together witha sulfur atom to which Q¹ and Q² are adjacent, an heteroalicyclic groupwhich may further contain an oxygen atom and a sulfur atom; Q³represents a hydrogen atom, Q⁴represents a straight chain or branchedalkyl group having from 1 to 6 carbon atoms or a cycloalkyl group havingfrom 3 to 10 carbon atoms, or Q³ and Q4 form, together with a CHC(O)group to which Q³ and Q4 are adjacent, a 2-oxocycloalkyl group; andQ⁵SO₃ ⁻ represents an organosulfonate ton, provided that when Q⁵represents a perfluoroalkyl group having from 1 to 8 carbon atoms, thereis excluded the case where Q¹ represents a straight chain or branchedalkyl group having from 1 to 6 carbon atoms, Q² represents a straightchain or branched alkyl group having from 1 to 6 carbon atoms, or acycloalkyl group having from 3 to 10 carbon atoms, and Q³ and Q⁴represent, together with their adjacent CHC(O) group, a 2-oxocycloalkylgroup, and

[0010] (b) at least one onium salt selected from a triphenylsulfoniumsalt represented by the following formula (IIa), and a diphenyliodoniumsalt represented by the following formula

[0011] wherein P¹ to P⁵ each independently represent hydrogen, ahydroxyl group, an alkyl group having from 1 to 6 carbon atoms, or analkoxy group having from 1 to 6 carbon atoms; and P⁶SO₃ ⁻ and P⁷SO₃ ⁻each independently represent an organosulfonate ion and

[0012] (B) a resin which has a polymerization unit having a groupinstable against an acid, and is alkali-insoluble or -slightly solubleitself, but is converted to alkali-soluble by the action of an acid.

[0013] Further, the present invention also provides a sulfonium saltrepresented by the following formula (Ia):

[0014] wherein Q⁶ represents a perfluoroalkyl group having from 1 to 8carbon atoms, an alkyl group having from 1 to 8 carbon atoms, anaromatic group having from 6 to 12 carbon atoms or a camphor group; whenQ⁶ represents a perfluoroalkyl group having from 1 to 8 carbon atoms, Q¹and Q² each independently represent a straight chain or branched alkylgroup having from 1 to 6 carbon atoms or a cycloalkyl group having from3 to 10 carbon atoms, or Q¹ and Q² form, together with a sulfur atom towhich Q¹ and Q² are adjacent, an heteroalicyclic group which may furthercontain an oxygen atom and a sulfur atom, Q³ represents a hydrogen atom,Q⁴ represents a straight chain or branched alkyl group having from 1 to6 carbon atoms or a cycloalkyl group having from 3 to 10 carbon atoms;when Q⁶ represents an alkyl group having from 1 to 8 carbon atoms, anaromatic group having from 6 to 12 carbon atoms or a camphor group, Q¹and Q² each independently represent a straight chain or branched alkylgroup having from 1 to 6 carbon atoms or a cycloalkyl group having from3 to 10 carbon atoms, or Q¹ and Q² form, together with a sulfur atom towhich Q¹ and Q² are adjacent, an heteroalicyclic group which may furthercontain an oxygen atom and a sulfur atom, Q³ represents a hydrogen atom,and Q⁴ represents a straight chain or branched alkyl group having from 1to 6 carbon atoms or a cycloalkyl group having from 3 to 10 carbonatoms, or Q³ and Q4 form, together with their adjacent CHC(O) group, a2-oxocycloalkyl group.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] As acid generator to be used for a chemical amplifying typeresist composition is decomposed to generate an acid by allowing aradiation such as light or an electron beam to act upon the substanceitself or a resist composition containing the substance. In thecomposition of the present invention, as such an acid generator, asulfonium salt represented by the formula (I), and at least one oniumsalt selected from a triphenylsulf onium salt represented by the formula(IIa), and a diphenyliodonium salt represented by the formula (IIb) areused in combination.

[0016] In the formula (I), Q¹ and Q² may be each independently an alkylgroup having from 1 to 6 carbon atoms, or a cycloalkyl group having from3 to 10 carbon atoms, and when they each have 3 or more carbon atoms,they may be strait-chain, or branched. Specific examples of an alkylgroup and a cycloalkyl group include methyl group, ethyl group, propylgroup, isopropyl group, butyl group, tert-butyl group, pentyl group,hexyl group, and cyclohexyl group. Further, examples of theheteroalicyclic group formed by Q¹ and Q² together with their adjacentsulfur atom include ethylene sulfide, trimethylene sulfide,tetrahydrothiophene, tetrahydrothiopyran, thioxane, dithiane,tetrahydrothiophene-3-one, and tetrahydrothiopyran-4-one. Among them,the heteroalicyclic group formed by Q¹ and Q² together with theiradjacent sulfur atom, which may further contain an oxygen atom and asulfur atom, is preferred in terms of thermal stability. If the thermalstability is good, it becomes possible to raise the bake temperature(PER temperature). Generally speaking, the roughness is improved with anincrease in PEB temperature. Further, Q³ may represent a hydrogen atom,Q⁴ may represent a straight chain or branched alkyl group having from 1to 6 carbon atoms or a cycloalkyl group having from 3 to 10 carbonatoms, or Q³ and Q⁴ may form, together with their adjacent CHC(O) group,a 2-oxocycloalkyl group. Specific examples of the alkyl group andcycloalkyl group as Q4 include methyl group, ethyl group, propyl group,isopropyl group, butyl group, tert-butyl group, pentyl group, hexylgroup, and cyclohexyl group. When Q³ and Q⁴ form, together with theiradjacent CHC(O) group, a 2-oxocycloalkyl group, examples of such a2-oxocycloalkyl group Include 2-oxocyclohexyl group, 2-oxocyclopentylgroup, camphor group, or the like.

[0017] In the formula (I), the Q⁵SO₃ ⁻ represents an organosulf oniumion. Q⁵ may be an organic group having about from 1 to 12 carbon atoms,for example. Examples of the organic group as Q⁵ include aperfluoroalkyl group having from 1 to 8 carbon atoms, an alkyl grouphaving from 1 to 8 carbon atoms, an aromatic group having from 6 to 12carbon atoms and a camphor group. Specific examples of theperfluoroalkyl group include trifluorornethyl group, perfluorobutylgroup, and perfluorooctyl group. Examples of the alkyl group having from1 to 8 carbon atoms include methyl group, ethyl group, propyl group,isopropyl group, butyl group, pentyl group, hexyl group, cyclbhexylgroup, and octyl group. Examples of the aromatic group include phenylgroup, tolyl group, xylyl group, mesityl group, and naphthyl group.

[0018] The sulfonium salt represented by the formula (I) can be producedin accordance with the method known in the art. For example, it can beproduced in accordance with the following reaction scheme by applyingthe method described in J. V. Crivello et al., “J. Polymer Science.,Polymer Chemistry Edition”, Vol.17, 2877-2892 (1979):

[0019] wherein Q¹, Q², Q³, Q⁴, and Q⁵ are as defined above; X representshalogen such as bromine or iodine; and M represents a hydrogen atom, analkali metal such as sodium or potassium, or silver.

[0020] Namely, β-halogenoketone corresponding to the formula (A2) isallowed to act upon a sulfide compound corresponding to the formula (A1)to form a sulfonium halide corresponding to the formula (B). Further, asulfonic acid or a metal salt of a sulfonic acid corresponding to theformula Q⁵SO₃M is allowed to act thereon. Consequently, a sulfonium saltrepresented by the formula (I) can be obtained. These reactions arecarried out in an appropriate solvent such as acetone, acetonitrile, ornitromethane The sulfide compound of the formula (A1) is used in a molarratio of preferably from 0.7 to 1.5, and more preferably from 0.8 to 1.1relative to β-halogenoketone corresponding to the formula (A2). Whereas,the sulfonic acid or the metal salt of a sulfonic acid corresponding tothe formula Q⁵SO₃M may be used in a molar ratio of from 0.7 to 1.2, andpreferably from 0.8 to 1.0 relative to the sulfide compound of theformula (A1) used for the formation of the sulfonium halide of theformula (B). After completion of the reaction, the halogenated metalsalt formed is removed by filtration or the like, and thenpost-treatments such as concentration and recrystallization areperformed. Consequently, a sulfonium salt of the formula (I) can beobtained.

[0021] Examples of the sulfonium salt represented by the formula (I)include:

[0022] dimethyl-(2-oxopropyl) sulfonium trifluoromethane sulfonate,

[0023] dimethyl-(2-oxobutyl)sulfonium trifluoromethane sulfonate,

[0024] dimethyl-(2-oxopentyl)sulfonium trifluoromethane sulfonate,

[0025] dimethyl-(2-oxohexyl)sulfonium trifluoromethane sulfonate,

[0026] dimethyl-(2-oxoheptyl)sulfonium trifluoromethane sulfonate,

[0027] dimethyl-(2-oxooctyl) sulfonium trifluoromethane sulfonate,

[0028] dimethyl-(3-methyl-2-oxobutyl)sulfonium trifluoromethanesulfonate,

[0029] 3.3-dimethyl-2-oxobutyl dimethylsulfonium trifluoromethanesulfonate,

[0030] 2-cyclohexyl-2-oxoethyl dimethylsulfonium trifluoromethanesulfonate,

[0031] 2-cyclopentyl-2-oxoethyl dimethylsulfonium trifluoromethanesulfonate,

[0032] diethyl-(2-oxopropyl)sulfonium trifluoromethane sulfonate,

[0033] diethyl-(2-oxobutyl)sulfonium trifluoromethane sulfonate,

[0034] diethyl-(2-oxopentyl)sulfonium trifluoromethane sulfonate,

[0035] diethyl-(2-oxohexyl)sulfonium trifluoromethane sulfonate,

[0036] diethyl-(2-oxoheptyl) sulfonium trifluoromethane sulfonate,

[0037] diethyl-(2-oxooctyl)sulfonium trifluoromethane sulfonate,

[0038] diethyl-(3-methyl-2-oxobutyl)sulfonium trifluoromethanesulfonate,

[0039] 3,3-dimethyl-2-oxobutyl diethylsulfonium trifluoromethanesulonate,

[0040] 2-cyclohexyl-2-oxoethyl diethylsulfonium trifluoromethanesulfonate,

[0041] 2-cyclopentyl-2-oxoethyl diethylsulfonium trifluoromethanesulfonate,

[0042] dibutyl-(2-oxopropyl) sulfonium trifluoromethane sulfonate,

[0043] dibutyl-(2-oxobutyl)sulfonium trifluoromethane sulfonate,

[0044] dibutyl-(2-oxopentyl)sulfonium trifluoromethane sulfonate,

[0045] dibutyl-(2-oxohexyl)sulfonium trifluoromethane sulfonate,

[0046] dibutyl-(2-oxoheptyl) sulfonium trifluoromethane sulfonate,

[0047] dibutyl-(2-oxooctyl)sulfonium trifluoromethane sulfonate,

[0048] dibutyl-(3-methyl-2-oxobutyl )sulfonium trifluoromethanesulfonate,

[0049] dibutyl-(3.3-dimethyl-2-oxobutyl) sulfonium trifluoromethanesulfonate,

[0050] dibutyl-(2-cyclohexyl-2-oxoethyl) sulfonium trifluoromethanesulfonate,

[0051] dibutyl-(2-cyclopentyl-2-oxoethyl) sulfonium trifluoromethanesulfonate,

[0052] diisopropyl-(2-oxopropyl)sulfonium trifluoromethane sulfonate,

[0053] diisopropyl-(2-oxobutyl)sulfonium trifluoromethane sulfonate,

[0054] diisopropyl-(2-oxopentyl)sulfonium trifluoromethane sulfonate,

[0055] diisopropyl-(2-oxohexyl)sulfonium trifluoromethane sulfonate,

[0056] diisopropyl-(2-oxoheptyl)sulfonium trifluoromethane sulfonate,

[0057] diisopropyl-(2-oxooctyl)sulfonium trifluoromethane sulfonate,

[0058] diisopropyl-(3-methyl-2-oxobutyl)sulfonium trifluoromethanesulfonate,

[0059] 3,3-dimethyl-2-oxobutyl diisopropylsulfoniur trifluoromethanesulfonate.

[0060] 2-cyclohexyl-2-oxoethyl diisopropylsulfonium trifluoromethanesulfonate,

[0061] 2-cyclopentyl-2-oxoethyl diisopropylsulfonium trifluoromethanesulfonate,

[0062] tert-butyl methyl(2-oxopropyl)sulfonium trifluoromethanesulfonate,

[0063] tert-butyl methyl(2-oxobutyl)sulfonium trifluoromethanesulfonate,

[0064] tert-butyl methyl(2-oxopentyl)sulfonium trifluoromethane

[0065] tert-butyl methyl(2-oxohexyl)sulfonium trifluoromethanesulfonate,

[0066] tert-butyl methyl(2-oxoheptyl)sulfonium trifluoromethanesulfonate,

[0067] tert-butyl methyl(2-oxooctyl)sulfonium trifluoromethanesulfonate,

[0068] tert-butyl methyl(3-methyl-2-oxobutyl)sulfonium trifluoromethanesulfonate,

[0069] tert-butyl (3,3-dimethyl-2-oxobutyl) methylsulfoniumtrifluoromethane sulfonate,

[0070] tert-butyl (2-cyclohexyl-2-oxoethyl) methylsulfoniumtrifluoromethane sulfonate.

[0071] tert-butyl (2-cyclopentyl-2-oxoethyl) methylsulfoniumtrifluoromethane sulfonate,

[0072] cyclohexyl methyl(2-oxopropyl)sulfonium trifluoromethanesulfonate,

[0073] cyclohexyl, methyl (2-oxobutyl) sulfonium trifluoromethanesulfonate,

[0074] cyclohexyl methyl(2-oxopentyl) sulfonium trifluoromethanesulfonate,

[0075] cyclohexyl methyl(2-oxohexyl)sulfonium trifluoromethanesulfonate,

[0076] cyclohexyl methyl(2-oxoheptyl)sulfonium trifluoromethanesulfonate,

[0077] cyclohexyl methyl(2-oxooctyl)sulfonium trifluoromethanesulfonate,

[0078] cyclohexyl methyl(3-methyl-2-oxobutyl)sulfonium trifluoromethanesulfonate,

[0079] cyclohexyl (3,3-dimethyl-2-oxobutyl) methylsulfonium,trifluoromethane sulfonate,

[0080] cyclohexyl (2-cyclohexyl-2-oxoethyl) methylsulfoniumtrifluoromethane sulfonate,

[0081] cyclohexyl (2-cyclopentyl-2-oxoethyl) methylsulfoniumtrifluoromethane sulfonate,

[0082] 2-oxopropyl thiaoyclopentanium trifluoromethane sulfonate,

[0083] 2-oxobutyl thiaoyclopentanium trifluoromethane sulfonate,

[0084] 2-oxopentyl thiaoyclopentanium trifluoromethane sulfonate,

[0085] 2-oxohexyl thiaoyclopentanium trifluoromethane sulfonate,

[0086] 2-oxoheptyl thiaoyclopentanium trifluoromethane sulfonate,

[0087] 2-oxooctyl thiaoyclopentanium trifluoromethane sulfonate,

[0088] 3-methyl-2-oxobutyl thiaoyclopentanium trifluoromethanesulfonate,

[0089] 3,3-dimethyl-2-oxobutyl thiaoyclopentanium trifluoromethanesulfonate,

[0090] 2-cyclohexyl-2-oxoethyl thiaoyclopentanium trifluoromethanesulfonate,

[0091] 2-cyclopentyl-2-oxoethyl thiaoyclopentanium trifluoromethanesulfonate,

[0092] 2-oxopropyl thiacyclohexanium trifluoromethane sulfonate,

[0093] 2-oxobutyl thiacyclohexanium trifluoromethane sulfonate,

[0094] 2-oxopentyl thiacyclohexanium trifluoromethane sulfonate,

[0095] 2-oxohexyl thiacyclohexanium trifluoromethane sulfonate,

[0096] 2-oxoheptyl thiacyclohexanium trifluoromethane sulfonate,

[0097] 2-oxooctyl thiacyclohexanium trifluoromethane sulfonate,

[0098] 3-methyl-2-oxobutyl thiacyclohexanium trifluoromethane sulfonate,

[0099] 3,3-dimethyl-2-oxobutyl thiacyclohexanium trifluoromethanesulfonate,

[0100] 2-cyclohexyl-2-oxoethyl thiacyclohexanium trifluoromethanesulfonate,

[0101] 2-cyclopentyl-2-oxoethyl thiacyclohexanium trifluoromethanesulfonate,

[0102] 2-oxopropyl (1l4-thioxane) trifluoromethane sulfonate,

[0103] 2-oxobutyl (1,4-thioxanium) trifluoromethane sulfonate,

[0104] 2-oxopentyl (1,4-thioxanium) trifluoromethane sulfonate,

[0105] 2-oxohexyl (1,4-thioxanium) trifluoromethane sulfonate,

[0106] 2-oxoheptyl (1,4-thioxanium) trifluoromethane sulfonate,

[0107] 2-oxooctyl (1,4-thioxanium) trifluoromethane sulfonate,

[0108] 3-methyl-2-oxobutyl (1,4-thioxanium) trifluoromethane sulfonate,

[0109] 3,3-dimethyl-2-oxobutyl (1,4-thioxanium) trifluoromethanesulfonate,

[0110] 2-cyclohexyl-2-oxoethyl (1,4-thioxanium) trifluoromethanesulfonate,

[0111] 2-cyclopentyl-2-oxoethyl (1,4-thioxanium) trifluoromethanesulfonate,

[0112] 2-oxopropyl (4-oxothiacyclohexanium) trifluoromethane sulfonate,

[0113] 2-oxobutyl (4-oxothiacyclohexanium) trifluoromethane sulfonate.

[0114] 2-oxopentyl (4-oxothiacyclohexanium) trifluoromethane sulfonate,

[0115] 2-oxohexyl (4-oxothiacyclohexanium) trifluoromethane sulfonate,

[0116] 2-oxoheptyl (4-oxothiacyclohexanium) trifluoromethane sulfonate,

[0117] 2-oxooctyl (4-oxothiacyclohexanium) trifluoromethane sulfonate,

[0118] 3-methyl-2-oxobutyl (4-oxothiacyclohexanium) trifluoromethanesulfonate,

[0119] 3,3-dimethyl-2-oxobutyl (4-oxothiacyclohexanium) trifluoromethanesulfonate,

[0120] 2-cyclohexyl-2-oxoethyl (4-oxothiacyclohexanium) trifluoromethanesulfonate,

[0121] 2-cyclopentyl-2-oxoethyl (4-oxothiacyclohexanium)trifluoromethane sulfonate,

[0122] 2-oxopropyl (1,4-dithianium) trifluoromethane sulfonate,

[0123] 2-oxobutyl (1,4-dithianium) trifluoromethane sulfonate,

[0124] 2-oxopentyl (1,4-dithianium) trifluoromethane sulfonate,

[0125] 2-oxohexyl (1,4-dithianium) trifluoromethane sulfonate,

[0126] 2-oxoheptyl (1,:4-dithianium) trifluoromethane sulfonate,

[0127] 2-oxoaetyl (1,4-dithianium) trifluoromethane sulfonate,

[0128] 3-methyl-2-oxobutyl (1,4-dithianium) trifluorom ethanenesulfonate,

[0129] 3,3-dimethyl-2-oxobutyl (1,4-dithianium) trifluoromethanesulfonate,

[0130] 2-cyclohexyl-2-oxoethyl (1,4-dithianium) trifluoromethanesulfonate,

[0131] 2-cyclopentyl-2-oxoethyl (1,4-dithianium) trifluoromethanesulfonate,

[0132] 2-oxoylohexylxy thiaoyclopentanium trifluoromethane sulfonate,

[0133] dimethyl-(2-oxopropyl)sulfonium perfluorobutane sulfonate,

[0134] dimethyl-(2-oxobutyl)sulfonium perfluorobutane sulfonate,

[0135] dimethyl-(2-oxopentyl)sulfonium perfluorobutane sulfonate,

[0136] dimethyl-(2-oxohexyl)sulfonium perfluorobutane sulfonate,

[0137] dimethyl-(2-oxoheptyl) sulfonium perfluorobutane sulfonate,

[0138] dimethyl-(2-oxooctyl)sulfonium perfluorobutane sulfonate,

[0139] dimethyl-(3-methyl-2-oxobutyl)sulfonium perfluorobutanesulfonate,

[0140] 3,3-dimethyl-2-oxobutyl dimethylsulfonium perfluorobutanesulfonate,

[0141] 2-cyclohexyl-2-oxoethyl dimethylsulfonium perfluorobutanesulfonate,

[0142] 2cyclopentyl-2-oxoethyl dimethylsulfonium perfluorobutanesulfonate;

[0143] diethyl-(2-oxopropyl)sulfonium perfluorobutane sulfonate,

[0144] diethyl-(2-oxobutyl)sulfonium perfluorobutane sulfonate,

[0145] diethyl-(2-oxopentyl)sulfonium perfluorobutane sulfonate,

[0146] diethyl-(2-oxohexyl)sulfonium perfluorobutane sulfonate,

[0147] diethyl-(2-oxoheptyl)sulfonium perfluorobutane sulfonate,

[0148] diethyl-(2-oxooctyl)sulfonium perfluorobutane sulfonate,

[0149] diethyl-(3-methyl-2-oxobutyl)sulfonium perfluorobutane sulfonate,

[0150] 3,3-dimethyl-2-oxobutyl diethylsulfonium perfluorobutanesulfonate,

[0151] 2-cyclohexyl-2-oxoethyl diethylsulfonium perfluorobutanesulfonate,

[0152] 2-cyclopentyl-2-oxoethyl diethylsulfonium perfluorobutanesulfonate,

[0153] dibutyl-(2-oxopropyl1)sulfonium perfluorobutane sulfonate,

[0154] dibutyl-(2-oxobutyl)sulfonium perfluorobutane sulfonate,

[0155] dibutyl (2-oxopentyl)sulfonium perfluorobutane sulfonate,

[0156] dibutyl-(2-oxohexyl)sulfonium perfluorobutane sulfonate,

[0157] dibutyl-(2-oxoheptyl)sulfonium perfluorobutane sulfonate,

[0158] dibutyl-(2-oxooctyl)sulfonium perfluorobutane sulfonate,

[0159] dibutyl-(3-methyl-2-oxobutyl)sulfonium perfluorobutane

[0160] sulfonate, dibutyl-(3,3-dimethyl-2-oxobutyl) sulfoniumperfluorobutane sulfonate,

[0161] dibutyl-(2-cyclohexyl-2-oxoethyl) sulfonium perfluorobutanesulfonate,

[0162] dibutyl-(2-cyclopentyl-2-oxoethyl) sulfonium perfluorobutanesulfonate,

[0163] diisopropyl-(2-oxopropyl)sulfonium perfluorobutane

[0164] sulfonate, diisopropyl-(2-oxobutyl)sulfonium perfluorobutanesulfonate,

[0165] diisopropyl-(2-oxopentyl)sulfonium perfluorobutane

[0166] sulfonate, diisopropyl-(2-oxohexyl)sulfonium perfluorobutanesulfonate,

[0167] diisopropyl-(2-oxoheptyl)sulfonium perfluorobutane

[0168] sulfonate, diisopropyl-(2-oxooctyl)sulfonium perfluorobutanesulfonate,

[0169] diisopropyl-(3-methyl-2-oxobutyl) sulfonium perfluorobutanesulfonate,

[0170] 3,3-dimethyl-2-oxobutyl diisopropylsulfonium perfluorobutanesulfonate,

[0171] 2-cyclohexyl-2-oxoethyl diisopropylsulfonium perfluorobutanesulfonate,

[0172] 2-cyclopentyl-2-oxoethyl diisopropylsulfonium perfluorobutanesulfonate,

[0173] tert-butyl methyl(2-oxopropyl)sulfonium perfluorobutanesulfonate,

[0174] tert-butyl methyl(2-oxobutyl)sulfonium perfluorobutane sulfonate,

[0175] tert -butyl methyl(2-oxopentyl)sulfonium perfluorobutanesulfonate,

[0176] tert-butyl methyl(2-oxohexyl)sulfonium perfluorobutane sulfonate,

[0177] tert-butyl methyl( 2-oxoheptyl) sulfonium perfluorobutanesulfonate,

[0178] tert-butyl methyl(2-oxooctyl)sulfonium perfluorobutane sulfonate,

[0179] tert-butyl methyl(3-methyl-2-oxobutyl)sulfonium perfluorobutanesulfonate,

[0180] tert-butyl (3,3-dimethyl-2-oxobutyl) methylsulfoniumperfluorobutane sulfonate,

[0181] tert-butyl (2-cyclohexyl-2-oxoethyl) methylsulfoniumperfluorobutane sulfonate,

[0182] tert-butyl (2-cyclopentyl-2-oxoethyl) methylsulfoniumperfluorobutane sulfonate,

[0183] cyclohexyl methyl (2-oxopropyl) sulfonium perfluorobutane

[0184] sulfonate, cyclohexyl methyl ( 2-oxobutyl) sulfoniumperfluorobutane sulfonate, cyclohexyl

[0185] methyl( 2-oxopentyl)sulfonium perfluorobutane sulfonate.

[0186] cyolohexyl methyl(2-oxohexyl) sulfonium perfluorobutanesulfonate,

[0187] cyclohexyl methyl(2-oxoheptyl)sulfonium perfluorobutanesulfonate,

[0188] cyclohexyl methyl(2-oxooctyl)sulfonium perfluorobutane sulfonate,

[0189] cyclohexyl methyl(3-methyl-2-oxobutyl)sulfonium perfluorobutanesulfonate,

[0190] cyclohexyl (3,3-dimethyl-2-oxobutyl) methylsulfoniumperfluorobutane sulfonate,

[0191] cyclohexyl (2-cyclohexyl-2-oxoethyl) inethylsulfoniumperfluorobutane sulfonate,

[0192] cyclohexyl (2-cyclopentyl-2-oxoethyl) methylsulfoniumperfluorobutane sulfonate,

[0193] 2-oxopropyl thiaoyclopentanium perfluorobutane sulfonate,

[0194] 2-oxobutyl thiacyclopentanium perfluorobutane sulfonate,

[0195] 2-oxopentyl thiacyclopentanium perfluorobutane sulfonate,

[0196] 2-oxohexyl thiacyclopentanium perfluorobutane sulfonate,

[0197] 2-oxopeptyl thiacyclopentanium perfluorobutane sulfonate,

[0198] 2-oxooctyl thiacyclopentanium perfluorobutane sulfonate,

[0199] 3-methyl-2oxo butyl thiacyclopentanium perfluorobutane sulfonate,

[0200] 3,3-dimethyl-2-oxobutyl thiacyclopentanium perfluorobutanesulfonate,

[0201] 2-cyclohexyl-2-oxoethyl thiacyclopentanium perfluorobutanesulfonate,

[0202] 2-cyclopentyl-2-oxoethyl thiacyclopentanium perfluorobutanesulfonate,

[0203] 2-oxopropyl thiacyclohexanium perfluorobutane sulfonate,

[0204] 2-oxobutyl thiacyclohexanium perfluorobutane sulfonate,

[0205] 2-oxopentyl thiacyclohexanium perfluorobutane sulfonate

[0206] 2-oxohexyl thiacyclohexanium perfluorobutane sulfonate,

[0207] 2-oxoheptyl thiacyclohexanium perfluorobutane sulfonate,

[0208] 2-oxoaetyl thiacyclohexanium perfluorobutane sulfonate,

[0209] 3-methyl-2-oxobutyl thiacyclohexanium perfluorobutane sulfonate,

[0210] 3,3-dimethyl-2-oxobutyl thiacyclohexanium perfluorobutanesulfonate,

[0211] 2-cyclohexyl-2-oxoethyl thiacyclohexanium perfluorobutanesulfonate.

[0212] 2-cyclopentyl-2-oxoethyl thiacyclohexanium perfluorobutanesulfonate,

[0213] 2-oxopropyl (1,4-thioxanium) perfluorobutane sulfonate,

[0214] 2-oxobutyl (1,4-thioxanium) perfluorobutane sulfonate,

[0215] 2-oxopentyl (1,4-thioxanium) perfluorobutane sulfonate,

[0216] 2-oxohexyl (1,4-thioxanium) perfluorobutane sulfonate,

[0217] 2-oxoheptyl (1,4-thioxanium) perfluorobutane sulfonate,

[0218] 2-oxooctyl (1,4-thioxanium) perfluorobutane sulfonate,

[0219] 3-methyl-2-oxo butyl (1,4-thioxanium) perfluorobutane sulfonate,

[0220] 3,3-dimethyl-2-oxobutyl (1,4-thioxanium) perfluorobutanesulfonate,

[0221] 2-cyclohexyl-2-oxoethyl (1,4-thioxanium) perfluorobutanesulfonate,

[0222] 2-cyclopentyl-2-oxoethyl (I,4-thioxanium) perfluorobutanesulfonate,

[0223] 2-oxopropyl (4-oxothiacyclohexanium) perfluorobutane sulfonate,

[0224] 2-oxobutyl (4-oxothiacyclohexanium) perfluorobutane sulfonate,

[0225] 2-oxopentyl (4-oxothiacyclohexanium) perfluorobutane sulfonate,

[0226] 2-oxohexyl (4-oxothiacyclohexanium) perfluorobutane sulfonate,

[0227] 2-oxopeptyl (4-oxothiacyclohexanium) perfluorobutane sulfonate,

[0228] 2-oxooctyl (4-oxothiacyclohexanium) perfluorobutane sulfonate,

[0229] 3-methyl-2-oxobutyl (4-oxothiacyclohexanium) perfluorobutanesulfonate,

[0230] 3,3-dimethyl-2-oxobutyl (4-oxothiacyclohexanium) perfluorobutanesulfonate,

[0231] 2-cyclohexyl-2-oxoethyl (4-oxothiacyclohexanium) perfluorobutanesulfonate,

[0232] 2-cyclopentyl-2-oxoethyl (4-oxothiacyclohexanium) perfluorobutanesulfonate,

[0233] 2-oxopropyl (1,4-dithianium) perfluorobutane sulfonate,

[0234] 2-oxobutyl (1,4-dithianium) perfluorobutane sulfonate,

[0235] 2-oxopentyl (1,4-dithianium) perfluorobutane sulfonate,

[0236] 2-oxohexyl (1,4-dithianium) perfluorobutane sulfonate,

[0237] 2-oxoheptyl (1,4-dithianium) perfluorobutane sulfonate,

[0238] 2-oxooctyl (1,4-dithianium) perfluorobutane sulfonate,

[0239] 3-methyl-2-oxobutyl (1,4-dithianium) perfluorobutane sulfonate,

[0240] 3,3-dimethyl-2-oxobutyl (1,4-dithianium) perfluorobutanesulfonate,

[0241] 2-cyclohexyl-2-oxoethyl (1,4-dithianium) perfluorobutanesulfonate,

[0242] 2-cyclopentyl-2-oxoethyl (1,4-dithianium) perfluorobutanesulfonate,

[0243] 2-oxocyclohexyl thiacyclopentanium perfluorobutane sulfonate,

[0244] dimethyl-(2-oxopropyl)sulfonium perfluorooctane sulfonate,

[0245] dimethyl-(2-oxobutyl)sulfonium perfluorooctane sulfonate,

[0246] dimethyl-(2-oxopentyl)sulfonium perfluorooctane sulfonate,

[0247] dimethyl-(2-oxohexyl)sulfonium perfluorooctane sulfonate,

[0248] dimethyl-(2-oxoheptyl)sulfonium perfluorooctane sulfonate,

[0249] dimethyl-(2-oxooctyl)sulfonium perfluorooctane sulfonate,

[0250] dimethyl-(3-methyl-2-oxobutyl)sulfonium perfluorooctanesulfonate,

[0251] 3,3-dimethyl-2-oxobutyl dimethylsulfonium perfluorooctanesulfonate,

[0252] 2-cyclohexyl-2-oxoethyl dimethylsulfonium perfluorooctanesulfonate,

[0253] 2-cyclopentyl-2-oxoethyl dimethylsulfonium perfluorooctanesulfonate,

[0254] diethyl-(2-oxopropyl)suifonium perfluorooctane sulfonate,

[0255] diethyl-(2-oxobutyl)suifonium perfluorooctane sulfonate,

[0256] diethyl-(2-oxopentyl)sulfonium perfluorooctane sulfonate,

[0257] diethyl-(2-oxohexyl)sulfonium perfluorooctane sulfonate,

[0258] diethyl-(2-oxoheptyl)sulfonium perfluorooctane sulfonate,

[0259] diethyl-(2-oxooctyl)suifonium perfluorooctane sulfonate,

[0260] diethyl-(3-methyl-2-oxobutyl)sulfonium perfluorooctane sulfonate,

[0261] 3,3-dimethyl-2-oxobutyl diethylsulfonium perfluorooctanesulfonate,

[0262] 2-cyclohexyl-2-oxoethyl diethylsulfonium perfluorooctanesulfonate,

[0263] 2-cyclopentyl-2-oxoethyl diethylsulfonium perfluorooctanesulfonate,

[0264] dibutyl-(2-oxopropyl)sulfonium perfluorooctane sulfonate,

[0265] dibutyl-(2-oxobutyl)sulfonium perfluorooctane sulfonate,

[0266] dibutyl-(2-oxopentyl)sulfonium perfluorooctane sulfonate,

[0267] dibutyl-(2-oxohexyl)sulfonium perfluorooctane sulfonate,

[0268] dibutyl-(2-oxoheptyl)sulfonium perfluorooctane sulfonate,

[0269] dibutyl-(2-oxooetyl)sulfonium perfluorooctane sulfonate,

[0270] dibutyl-(3-methyl-2-oxobutyl)sulfonium perfluorooctane sulfonate,

[0271] dibutyl-(3,3-dimethyl -2-oxobutyl) sulfonium perfluorooctanesulfonate,

[0272] dibutyl-(2-cyclohexyl-2-oxoethyl) sulfonium perfluorooctanesulfonate,

[0273] dibutyl-(2-cyclopentyl-2-oxoethyl) sulfonium perfluorooctanesulfonate,

[0274] diisopropyl-(2-oxopropyl) sulfonium perfluorooctane

[0275] sulfonate, diisopropyl-(2-oxobutyl)sulfonium perfluorooctanesulfonate,

[0276] diisopropyl-(2-oxopentyl)sulfonium perfluorooctane

[0277] sulfonate, diisopropyl-(2-oxohexyl)sulfonium perfluorooctanesulfonate,

[0278] diisopropyl-(2-oxohaptyl)sulfonium perfluorooctane

[0279] sulfonate, diisopropyl-(2-oxooctyl)sulfonium perfluorooctanesulfonate,

[0280] diisopropyl-(3-methyl-2-oxobutyl) sulfonium perfluorooctanesulfonate,

[0281] 3,3-dimethyl-2-oxobutyl diisopropylsulfonium perfluorooctanesulfonate,

[0282] 2-cyclohexyl-2-oxoethyl diisopropylsulfonium perfluorooctanesulfonate,

[0283] 2-cyclopentyl-2-oxoethyl diisopropylsulfonium perfluorooctanesulfonate,

[0284] tert-butyl methyl(2-oxopropyl)sulfonium perfluorooctanesulfonate,

[0285] tert-butyl methyl(2-oxobutyl)sulfonium perfluorooctane sulfonate,

[0286] tert-butyl methyl(2-oxopentyl)sulfonium perfluorooctanesulfonate,

[0287] tert-butyl methyl(2-oxohexyl)sulfonium perfluorooctane sulfonate,

[0288] tert-butyl methyl(2-oxoheptyl)sulfonium perfluorooctanesulfonate,

[0289] tert-butyl methyl(2-oxooctyl)sulfonium perfluorooctane sulfonate,

[0290] tert-butyl methyl(3-methyl-2-oxobutyl)sulfonium perfluorooctanesulfonate,

[0291] tert-butyl (3,3-dimethyl-2-oxobutyl) methylsulfoniumperfluorooctane sulfonate,

[0292] tert-butyl (2-cyclohexyl-2-oxoethyl) methylsulfoniumperfluorooctane sulfonate,

[0293] tert-butyl (2-cyclopentyl-2-oxoethyl) methylsulfoniumperfluorooctane sulfonate,

[0294] cyclohexyl methyl(2-oxopropyl)sulfonium perfluorooctane

[0295] sulonate, cyolohexyl methyl(2-oxobutyl)sulfonium perfluorooctanesulfonate, cyclohexyl

[0296] methyl(2-oxopentyl)sulfonium perfluorooctane sulfonate,

[0297] cyclohexyl methyl(2-oxohexyl)sulfonium perfluorooctane sulfonate,

[0298] cyclohexyl methyl(2-oxoheptyl)sulfonium perfluorooctanesulfonate,

[0299] cyclohexyl methyl(2-oxooctyl)sulfonium perfluorooctane sulfonate,

[0300] cyclohexyl methyl(3-methyl-2-oxobutyl)sulfonium perfluorooctanesulfonate,

[0301] cyclohexyl (3,3-dimethyl-2-oxobutyl) sulfonium perfluorooctanesulfonate,

[0302] cyclohexyl (2-cyclohexyl-2-oxoethyl) methylsulfoniumperfluorooctane sulfonate,

[0303] cyclohexyl (2cyclopentyl-2-oxoethyl) methylsulfoniumperfluorooctane sulfonate,

[0304] 2-oxopropyl thiacyclopentanium perfluorooctane methylsulfonate,

[0305] 2-oxobutyl thiacyclopentanium perfluorooctane sulfonate,

[0306] 2-oxopentyl thiacyclopentaniur perfluorooctane sulfonate,

[0307] 2-oxohexyl thiacyclopentanium perfluorooctane sulfonate,

[0308] 2-oxoheptyl thiacyclopentantum perfluorooctane sulfonate,

[0309] 2-oxooctyl thiacyclopentanium perfluorooctane sulfonate,

[0310] 3-methyl-2-oxobutyl thiacyclopentanium perfluorooctane sulfonate,

[0311] 3,3-dimethyl-2-oxobutyl thiacyclopentanium perfluorooctanesulfonate,

[0312] 2-cyclohexyl-2-oxoethyl thiacyclopentanium perfluorooctanesulfonate,

[0313] 2-cyclopentyl-2-oxoethyl thiacyclopentanium perfluorooctanesulfonate,

[0314] 2-oxopropyl thiacyclohexanium perfluorooctane sulfonate,

[0315] 2-oxobutyl thiacyclohexanium perfluorooctane sulfonate,

[0316] 2-oxopentyl thiacyclohexanium perfluorooctane sulfonate,

[0317] 2-oxohexyl thiacyclohexanium perfluorooctane sulfonate,

[0318] 2-oxoheptyl thiacyclohexanium perfluorooctane sulfonate,

[0319] 2-oxooctyl thilcyclohexanium perfluorooctane sulfonate,

[0320] 3-methyl-2-oxobutyl thiacyclohexanium perfluorooctane sulfonate,

[0321] 3,3-dimethyl-2-oxobutyl thiacyclohexanium perfluorooctanesulfonate,

[0322] 2-cyclohexyl-2-oxoethyl thiacyclohexanium perfluorooctanesulfonate,

[0323] 2-cyclopentyl-2-oxoethyl thiacyclohexanium perfluorooctanesulfonate,

[0324] 2-oxopropyl (1, 4-thioxanium) perfluorooctane sulfonate

[0325] 2-oxobutyl (1,4-thioxanium) perfluorooctane sulfonate,

[0326] 2-oxopentyl (1,4-thioxanium) perfluorooctane sulfonate,

[0327] 2-oxohexyl (1, 4-thioxanium) perfluorooctane sulfonate,

[0328] 2-oxoheptyl (1,4-thioxanium) perfluorooctane sulfonate,

[0329] 2-oxooctyl (1, 4-thioxanium) perfluorooctane sulfonate,

[0330] 3-methyl-2-oxobutyl (1, 4-thioxanium) perfluorooctane sulfonate,

[0331] 3,3-dimethyl-2-oxobutyl (1,4-thioxanium) perfluorooctanesulfonate,

[0332] 2-cyclohexyl-2-oxoethyl (1,4-thioxanium) perfluorooctanesulfonate,

[0333] 2-cyclopentyl-2-oxoethyl (1,4-thioxanium) perfluorooctanesulfonate,

[0334] 2-oxopropyl (4-oxothiacyclohexanium) perfluorooctane sulfonate,

[0335] 2-oxobutyl (4-oxothiacyclohexanium) perfluorooctane sulfonate,

[0336] 2-oxopentyl (4-oxothiacyclohexanium) perfluorooctane sulfonate,

[0337] 2-oxohexyl (4-oxothiacyclohexanium) perfluorooctane sulfonate,

[0338] 2-oxoheptyl (4-oxothiacyclohexanium) perfluorooctane sulfonate,

[0339] 2-oxooctyl (4-oxothiacyclohexanium) perfluorooctane sulfonate,

[0340] 3-methyl-2-oxobutyl (4-oxothiacyclohexanium) perfluorooctanesulfonate,

[0341] 3,3-dimethyl-2-oxobutyl (4-oxothiacyclohexanium) perfluorooctanesulfonate,

[0342] 2-cyolohexyl-2-oxoethyl (4-oxothiacyclohexanium) perfluorooctanesulfonate,

[0343] 2-cyclopentyl-2-oxoethyl (4-oxothiacyclohexanium) perfluorooctanesulfonate,

[0344] 2-oxopropyl (1,4-dithianium) perfluorooctane sulfonate,

[0345] 2-oxobutyl (1,4-dithianium) perfluorooctane sulfonate,

[0346] 2-oxopentyl (1,4-dithianium) perfluorooctane sulfonate,

[0347] 2-oxohexyl (1,4-dithianium) perfluorooctane sulfonate,

[0348] 2-oxoheptyl (1,4-dithianium) perfluorooctane sulfonate,

[0349] 2-oxooctyl (1,4-dithianium) perfluorooctane sulfonate,

[0350] 3-methyl-2-oxobutyl (1,4-dithianium) perfluorooctane sulfonate,

[0351] 3,3-dimethyl-2-oxobutyl (1.4-dithianium) perfluorooctanesulfonate,

[0352] 2-cyclohexyl-2-oxoethyl (1,4-dithianium) perfluorooctanesulfonate,

[0353] 2-cyclopentyl-2-oxoethyl (1,4-dithianium) perfluorooctanesulfonate,

[0354] 2-oxocyclohexyl thiacyclopentanium perfluorooctane

[0355] dimethyl-(2-oxopropyl)sulfonium butane sulfonate,

[0356] dimethyl-(2-oxobutyl)sulfonium butane sulfonate,

[0357] dimethyl-(2-oxopentyl)sulfonium butane sulfonate,

[0358] dimethyl-(2-oxohexyl)sulfonium butane sulfonate,

[0359] dimethyl-(2-oxoheptyl)sulfonium butane sulfonate,

[0360] dimethyl-(2-oxooctyl)sulfonium butane sulfonate,

[0361] dimethyl-(3-methyl-2-oxobutyl)sulfonium butane sulfonate,

[0362] 3,3-dimethyl-2-oxobutyl dimethylsulfonium butane sulfonate,

[0363] 2-cyclohexyl-2-oxoethyl dimethylsulfonium butane sulfonate,

[0364] 2-cyclopentyl-2-oxoethyl dimethylsulfonium butane sulfonate,

[0365] diethyl-(2-oxopropyl)sulfonium butane sulfonate,

[0366] diethyl-(2-oxobutyl)sulfonium butane sulfonate,

[0367] diethyl-(2-oxopentyl)sulfonium butane sulfonate,

[0368] diethyl-(2-oxohexyl)sulfonium butane sulfonate,

[0369] diethyl-(2-oxoheptyl)sulfonium butane sulfonate,

[0370] diethyl-(2-oxooctyl)sulfonium butane sulfonate,

[0371] diethyl-(3-methyl-2-oxobutyl)sulfonium butane sulfonate,

[0372] 3,3-dimethyl-2-oxobutyl diethylsulfonium butane sulfonate,

[0373] 2-cyclohexyl-2-oxoethyl diethylsulfonium butane sulfonate,

[0374] 2-cyclopentyl-2-oxoethyl diethylsulfoniumbutane sulfonate,

[0375] dibutyl-(2-oxopropyl)sulfonium butane sulfonate,

[0376] dibutyl-(2-oxobutyl)sulfonium butane sulfonate,

[0377] dibutyl-(2-oxopentyl)sulfonium butane sulfonate,

[0378] dibutyl-(2-oxohexyl)sulfonium butane sulfonate,

[0379] dibutyl-(2-oxoheptyl)sulfonium butane sulfonate,

[0380] dibutyl-(2-oxooctyl)sulfonium butane sulfonate,

[0381] dibutyl-(3-methyl-2-oxobutyl)sulfonium butane sulfonate,

[0382] dibutyl-(3,3-dimethyl-2-oxobutyl) sulfonium butane sulfonate,

[0383] dibutyl-(2-cyclohexyl-2-oxoethyl) sulfonium butane sulfonate,

[0384] dibutyl-(2-cyclopentyl-2-oxoethyl) sulfonium butane sulfonate,

[0385] diisopropyl-(2-oxopropyl)sulfonium butane sulfonate,

[0386] diisopropyl-(2-oxobutyl)sulfonium, butane sulfonate,

[0387] diisopropyl-(2-oxopentyl)sulfonium butane sulfonate,

[0388] diisopropyl-( 2-oxohexyl) sulfonium butane sulfonate,

[0389] diisopropyl-( 2-oxoheptyl) sulfonium butane sulfonate,

[0390] diisopropyl-(2-oxooctyl)sulfonium butane sulfonate,

[0391] diisopropyl-(3-methyl-2-oxobutyl)sulfonium butane sulfonate,

[0392] 3,3-aimethyl-2-oxobutyl diisopropylsulfonium butane sulfonate,

[0393] 2-cyelohexyl-2-oxoethyl diisopropylsulfonium butane sulfonate,

[0394] 2-cyclopentyl-2-oxoethyl diisopropylsulfonium butane sulfonate,

[0395] tert-butyl methyl(2-oxopropyl)sulfonium butane sulfonate,

[0396] tert-butyl methyl(2-oxobutyl)sulfonium butane sulfonate,

[0397] tert-butyl methyl(2-oxopentyl)sulfonium butane sulfonate,

[0398] tert-butyl methyl(2-oxohexyl)sulfonium butane sulfonate,

[0399] tert-butyl methyl(2-oxoheptyl)sulfonium butane sulfonate,

[0400] tert-butyl methyl(2-oxooctyl)sulfonium butane sulfonate,

[0401] tert-butyl methyl(3-methyl-2-oxobutyl sulfonium butane sulfonate,

[0402] tert-butyl (3, 3-dimethyly-2-oxobutyl) methylsulfonium butanesulfonate,

[0403] tert-butyl (2-cyclohexyl-2-oxoethyl) methylsulfonium butanesulfonate,

[0404] tert-butyl (2-cyclopentyl-2-oxoethyl) methylsulfonium butanesulfonate,

[0405] cyclohexyl methyl(2-oxopropyl)sulfonium butane sulfonate,

[0406] cyclohexyl methyl(2-oxobutyl)sulfonium butane sulfonate,

[0407] cyclohexyl methyl(2-oxopentyl)sulfonium butane sulfonate,

[0408] cyclohexyl methyl(2-oxohexyl)sulfonium butane sulfonate,

[0409] cyclohexyl methyl(2-oxoheptyl)suifonium butane sulfonate,

[0410] cyclohexyl methyl(2-oxooctyl)sulfonium butane sulfonate,

[0411] cyclohexyl methyl(3-methyl-2-oxobutyl)sulfonium butane sulfonate,

[0412] cyclohexyl (3,3-dimethyl-2-oxobutyl) methylsulfonium butanesulfonate,

[0413] cyclohexyl (2-cyclohexyl-2-oxoethyl) methylsulfonium butanesulfonate,

[0414] cyclohexyl (7-cyclopentyl-2-oxoethyl) methylsulfonium butanesulfonate.

[0415] 2-oxopropyl thiacyclopentanium butane sulfonate,

[0416] 2-oxobutyl thiacyclopentanium butane sulfonate,

[0417] 2-oxopentyl thiacyclopentanium butane sulfonate,

[0418] 2-oxohexyl thiacyclopentanium butane sulfonate,

[0419] 2-oxoheptyl thiacyclopentanium butane sulfonate,

[0420] 2-oxooctyl thiaoyclopentanium butane sulfonate,

[0421] 3-methyl-2-oxobutyl thiacyclopentanium butane sulfonate,

[0422] 3,3-dimethyl-2-oxobutyl thiacyclopentanium butane sulfonate,

[0423] 2-cyclohexyl-2-oxoethyl thiacyclopentaniur butane sulfonate,

[0424] 2-cyclopentyl-2-oxoethyl thiacyclopentanium butane sulfonate,

[0425] 2-oxopropyl thiacyclohexanium butane sulfonate,

[0426] 2-oxobutyl thiacyclohexanium butane sulfonate,

[0427] 2-oxopentyl thiacyclohexanium butane sulfonate,

[0428] 2-oxohexyl thiacyclohexanium butane sulfonate,

[0429] 2-oxoheptyl thiacyclohexanium butane sulfonate,

[0430] 2-oxooctyl thiacyclohexanium butane sulfonate,

[0431] 3-methyl-2-oxobutyl thiacyclohexanium butane sulfonate,

[0432] 3,3-dimethyl-2-oxobutyl thiacyclohexanium butane sulfonate,

[0433] 2-cyclohexyl-2-oxoethyl thiacyclohexanium butane sulfonate,

[0434] 2-cyclopentyl-2-oxoethyl thiacyclohexanium butane sulfonate,

[0435] 2-oxopropyl (1,4-thioxanium) butane sulfonate,

[0436] 2-oxobutyl (1,4-thioxanium) butane sulfonate,

[0437] 2-oxopentyl (1,4-thioxanium) butane sulfonate,

[0438] 2-oxohexyl (1,4-thioxanium) butane sulfonate,

[0439] 2-oxoheptyl (1,4-thioxanium) butane sulfonate,

[0440] 2-oxooctyl (1,4-thioxanium) butane sulfonate,

[0441] 3-methyl-2-oxobutyl (1,4-thioxanium) butane sulfonate,

[0442] 3,3-dimethyl-2-oxobutyl (1,4-thioxanium) butane sulfonate,

[0443] 2-cyclohexyl-2-oxoethyl (1,4-thioxanium) butane sulfonate,

[0444] 2-cyclopentyl-2-oxoethyl (1,4-thioxanium) butane sulfonate,

[0445] 2-oxopropyl (4-oxothiacyclohexanium) butane sulfonate,

[0446] 2-oxobutyl (4-oxothiacyclohexanium) butane sulfonate,

[0447] 2-oxopentyl (4-oxothiacyclohexanium) butane sulfonate,

[0448] 2-oxohexyl (4-oxothiacyclohexanium) butane sulfonate,

[0449] 2-oxoheptyl (4-oxothiacyclohexanium) butane sulfonate,

[0450] 2-oxooctyl (4-oxothiacyclohexanium) butane sulfonate,

[0451] 3-methyl-2-oxo butyl (4-oxothiacyclohexanium) butane sulfonate,

[0452] 3,3-dimethyl-2-oxobutyl (4-oxothiacyclohexanium) butanesulfonate,

[0453] 2-cyclohexyl-2-oxoethyl (4-oxothiacyclohexanium) butanesulfonate,

[0454] 2-cyclopentyl-2-oxoethyl (4-oxothiacyclohexanium) butanesulfonate,

[0455] 2-oxopropyl (1,4-dithianium) butane sulfonate,

[0456] 2-oxobutyl (1,4-dithianium) butane sulfonate,

[0457] 2-oxopentyl (1,4-dithianium) butane sulfonate,

[0458] 2-oxohexyl (1,4-dithianium) butane sulfonate,

[0459] 2-oxoheptyl (1,4-dithianium) butane sulfonate,

[0460] 2-oxooctyl (1,4-dithianium) butane sulfonate,

[0461] 3-methyl-2-oxobutyl (1,4-dithianium) butane sulfonate,

[0462] 3,3-dimethyl-2-oxobutyl (1,4-dithianium) butane sulfonate,

[0463] 2-cyclohexyl-2-oxoethyl (1,4-dithianium) butane sulfonate,

[0464] 2-cyclopentyl-2-oxoethyl (3, 4-dithianium) butane sulfonate,

[0465] 2-oxocyclohexyl thiacyclopentanium butane sulfonate,

[0466] dimethyl-i2-oxopropyl)sulfonium p-toluene sulfonate,

[0467] dimethyl-(2-oxobutyl)sulfonium p-toluene sulfonate,

[0468] dimethyl-(2-oxopentyl)sulfonium p-toluene sulfonate,

[0469] dimethyl-(2-oxohexyl)sulfonium p-toluene sulfonate,

[0470] dimethyl-(2-oxoheptyl)sulfonium p-toluene sulfonate,

[0471] dimethyl-(2-oxooctyl)sulfonium p-toluene sulfonate,

[0472] dimethyl-(3-methyl-2-oxo butyl )sulfonium p-toluene sulfonate,

[0473] 3,3-dimethyl-2-oxobutyl dimethylsulfonium p-toluene sulfonate,

[0474] 2-cyclohexyl-2-oxoethyl dimethylsulfonium p-toluene sulfonate,

[0475] 2-cyclopentyl-2-oxoethyl dimethylsulfonium p-toluene sulfonate,

[0476] diethyl-(2-oxopropyl) sulfonium p-toluene sulfonate,

[0477] diethyl(2-oxobutyl)sulfonium p-toluene sulfonate,

[0478] diethyl-(2-oxopentyl)sulfonium p-toluene sulfonate,

[0479] diethyl-(2-oxohexyl)sulfonium p-toluene sulfonate,

[0480] diethyl-(2-oxoheptyl)sulfonium p-toluene sulfonate,

[0481] diethyl-(2-oxooctyl)sulfonium p-toluene sulfonate

[0482] diethyl-(3-methyl-2-oxobutyl)sulfonium p-toluene sulfonate,

[0483] 3,3-dimethyl-2-oxobutyl diethylsulfonium p-toluene sulfonate,

[0484] 2-cyclohexyl-2-oxoethyl diethylsulfonium p-toluene sulfonate,

[0485] 2-cyclopentyl-2-oxoethyl diethylsulfonium p-toluene sulfonate,

[0486] dibutyl-(2-oxopropyl)sulfonium p-toluene sulfonate,

[0487] dibutyl-(2-oxobutyl)sulfonium p-toluene sulfonate,

[0488] dibutyl-(2-oxopentyl)sulfonium p-toluene sulfonate,

[0489] dibutyl-(2-oxohexyl)sulfonium p-toluene sulfonate,

[0490] dibutyl-(2-oxoheptyl)sulfonium p-toluene sulfonate,

[0491] dibutyl-(2-oxooctyl)sulfonium p-toluene sulfonate,

[0492] dibutyl-(3-methyl-2-oxobutyl)sulfonium p-toluene sulfonate,

[0493] dibutyl-(3,3-dimethyl-2-oxobutyl) sulfonium p-toluene sulfonate,

[0494] dibutyl-(2-cyclohexyl-2-oxoethyl) sulfonium p-toluene sulfonate,

[0495] dibutyl-(2-cyclopentyl-2-oxoethyl) sulfonium p-toluene sulfonate,

[0496] diisopropyl-(2-oxopropyl)sulfonium p-toluene sulfonate,

[0497] diisopropyl-(2-oxobutyl)sulfonium p-toluene sulfonate,

[0498] diisopropyl-(2-oxopentyl)sulfonium p-toluene sulfonate.

[0499] diisopropyl-(2-oxohexyl)sulfonium p-toluene sulfonate,

[0500] diisopropyl-(2-oxoheptyl)sulfonium p-toluene sulfonate,

[0501] diisopropyl-(2-oxooctyl)sulfonium p-toluene sulfonate,

[0502] diisopropyl-(3-methyl-2-oxobutyl)sulfonium p-toluene sulfonate,

[0503] 3,3-dimethyl-2-oxobutyl diisopropylsulfonium p-toluene sulfonate,

[0504] 2-cyclohexyl-2-oxoethyl diisopropylsulfonium p-toluene sulfonate,

[0505] 2-cyclopentyl-2-oxoethyl diisopropylsulfonium p-toluenesulfonate,

[0506] tert-butyl methyl(2-oxopropyl)sulfonium p-toluene sulfonate,

[0507] tert-butyl methyl(2-oxobutyl) sulfonium-toluene sulfonate,

[0508] tert-butyl methyl(2-oxopentyl) sulfonium-toluene sulfonate,

[0509] tert-butyl methyl(2-oxohexyl)sulfonium p-toluene sulfonate,

[0510] tert-butyl methyl(2-oxoheptyl) sulfonium-toluene sulfonate,

[0511] tert-butyl methyl(2-oxooctyl)sulfonium p-toluene sulfonate,

[0512] tert-butyl methyl(3methyl-2-oxobutyl)sulfonium p-toluenesulfonate,

[0513] tert-butyl (3,3-dimethyl-2-oxobutyl) methylsulfonium p-toluenesulfonate,

[0514] tert-butyl (2-cyclohexyl-2-oxoethyl) methylsulfonium p-toluenesulfonate,

[0515] tert-butyl (2-cyclopentyl-2-oxoethyl) methylsulfonium p-toluenesulfonate,

[0516] cyclohexyl methyl ( 2-oxopropyl) sulfonium p-toluene sulfonate,

[0517] cyclohexylmethyl(2-oxobutyl) sulfonium p-toluene sulfonate,

[0518] cyclohexyl methyl(2-oxopentyl)sulfonium p-toluene sulfonate,

[0519] cyclohexylmethyl(2-oxohexyl)sulfonium-toluene sulfonate,

[0520] cyclohexyl methyl(2-oxoheptyl)sulfonium p-toluene sulfonate,

[0521] cyclohexyl methyl(2-oxooctyl)sulfonium p-toluene sulfonate,

[0522] cyclohexyl methyl(3-methyl-2-oxobutyl)sulfonium p-toluenesulfonate,

[0523] cyclohexyl (3,3-dimethyl-2-oxobutyl) methylsulfonium p-toluenesulfonate.

[0524] cyclohexyl (2-cyclohexyl-2-oxoethyl) methylsulfonium p-toluenesulfonate,

[0525] cyclohexyl (2-cyclopentyl-2-oxoethyl) methylsulfonium p-toluenesulfonate.

[0526] 2-oxopropyl thiacyclopentanium p-toluene sulfonate,

[0527] 2-oxobutyl thiacyclopentanium p-toluene sulonate,

[0528] 2-oxopentyl thiacyclopentaniur p-toluene sulfonate,

[0529] 2-oxohexyl thiacyclopentanium p-toluene sulfonate,

[0530] 2-oxoheptyl thiacyclopentanium p-toluene sulfonate,

[0531] 2-oxooctyl thiacyclopentanium p-toluene sulfonate,

[0532] 3-methyl 2-oxobutyl thiacyclopentanium p-toluene sulfonate,

[0533] 3, 3-dimethyl i-oxobutyl thiacyclopentanium p-toluene sulfonate,

[0534] 2-cyclbhexyl-2-oxoethyl thiacyclopentanium p-toluene sulfonate,

[0535] 2-cyclopentyl-2-oxoethyl thiacyclopentanium p-toluene sulfonate,

[0536] 2-oxopropyl thiacyclohexanium p-toluene sulfonate,

[0537] 2-oxobutyl thiacyclohexanium p-toluene sulfonate,

[0538] 2-oxopentyl thiacyclohexanium p-toluene sulfonate,

[0539] 2-oxohexyl thiacyclohexanium p-toluene sulfonate,

[0540] 2-oxoheptyl thiacyclohexanium p-toluene sulfonate,

[0541] 2-oxooctyl thiacyclohexanium p-toluene sulfonate,

[0542] 3-methyl-2-oxobutyl thiacyclohexanium p-toluene sulfonate,

[0543] 3.3-dimethyl-2-oxobutyl thiacyclohexanium p-toluene sulfonate,

[0544] 2-cyolohexyl-2-oxoethyl thiacyclohexanium p-toluene sulfonate,

[0545] 2-cyclopentyl-2-oxoethyl thiacyclohexanium p-toluene sulfonate,

[0546] 2-oxopropyl (1,4-thioxanium) p-toluene sulfonate,

[0547] 2-oxobutyl (1,4-thioxanium) p-toluene sulfonate,

[0548] 2-oxopentyl (1.,4-thioxanium) p-toluene sulfonate,

[0549] 2-oxohexyl (1,4-thioxanium) p-toluene sulfonate,

[0550] 2-oxoheptyl (1.4-thioxanium) p-toluene sulfonate,

[0551] 2-oxooctyl (1i4-thioxanium) p-toluene sulfonate,

[0552] 3-methyl-2-oxobutyl (I,4-thioxanium ) p-toluene sulfonate

[0553] 3,3-dimethyl-2-oxobutyl (1,4-thioxanium ) p-toluene

[0554] 2-cyclohexyl-2-oxoethyl (1,4-thioxanium) p-toluene sulfonate,

[0555] 2-cyclopentyl-2-oxoethyl (1,4-thioxanium) p-toluene sulfonate,

[0556] 2-oxopropyl (4-oxothiacyclohexanium) p-toluene sulfonate,

[0557] 2-oxobutyl (4-oxothiacyclohexanium) p-toluene sulfonate,

[0558] 2-oxopentyl (4-oxothiacyclohexanium) p-toluene sulfonate,

[0559] 2-oxohexyl (4-oxothiacyclohexanium) p-toluene sulfonate,

[0560] 2-oxoheptyl (4-oxothiacyclohexanium) p-toluene sulfonate,

[0561] 2-oxooctyl (4-oxothiacyclohexanium) p-toluene sulfonate,

[0562] 3-methyl-2-oxobutyl (4-oxothiacyclohexanium) p-toluene sulfonate,

[0563] 3,3-dimethyl-2-oxobutyl (4-oxothiacyclohexanium) p-toluenesulfonate,

[0564] 2-cyclohexyl-2-oxoethyl (4-oxothiacyclohexanium) p-toluenesulfonate,

[0565] 2-cyclopentyl-2-oxoethyl (4-oxothiacyclohexanium) p-toluenesulfonate,

[0566] 2-oxopropyl (1,4-dithianium) p-toluene sulfonate,

[0567] 2-oxobutyl (1,4-dithianium) p-toluene sulfonate,

[0568] 2-oxopentyl (1,4-dithianium) p-toluene sulfonate,

[0569] 2-oxohexyl (1,4-dithianium) p-toluene sulfonate,

[0570] 2-oxoheptyl (1,4-dithianium) p-toluene sulfonate,

[0571] 2-oxooctyl (1,4-dithianium) p-toluene sulfonate,

[0572] 3-methyl-2-oxobutyl (1 4-dithianium) p-toluene sulfonate,

[0573] 3,3-dimethyl-2-oxobutyl (1,4-dithianium) p-toluene sulfonate,

[0574] 2-cyclohexyl-2-oxoethyl (1,4-dithianium) p-toluene sulfonate,

[0575] 2-cyclopentyl-2-oxoethyl (1,4-dithianium) p-toluene sulfonate,

[0576] 2-oxocyclohexyl thiacyclopentanium p-toluene sulfonate,

[0577] dimethyl-(2-oxopropyl)sulfonium camphor sulfonate,

[0578] dimethyl-(2-oxobutyl)sulfonium camphor sulfonate,

[0579] dimethyl-(2-oxopentyl)sulfonium camphor sulfonate,

[0580] dimethyl-(2-oxohexyl)sulfonium camphor sulfonate,

[0581] dimethyl-(2-oxoheptyl)sulfonium camphor sulfonate,

[0582] dimethyl-(2-oxooctyl)sulfonium camphor sulfonate,

[0583] dimethyl-(3-methyl-2-oxobutyl)sulfonium camphor sulfonate,

[0584] 3,3-dimethyl-2-oxobutyl dimethylsulfonium camphor sulfonate,

[0585] 2-cyclohexyl-2-oxoethyl dimethylsulfonium camphor sulfonate,

[0586] 2-cyclopentyl-2-oxoethyl dimethylsulfonium camphor sulfonate,

[0587] diethyl-(2-oxopropyl)sulfonium camphor sulfonate,

[0588] diethyl-(2-oxobutyl)sulfonium camphor sulfonate,

[0589] diethyl-(2-oxopentyl)sulfonium camphor sulfonate,

[0590] diethyl-(2-oxohexyl)sulfonium camphor sulfonate,

[0591] diethyl-(2-oxoheptyl)sulfonium camphor sulfonate,

[0592] diethyl-(2-oxooctyl)sulfonium camphor sulfonate,

[0593] diethyl-(3-methyl-2-oxobutyl)sulfonium camphor sulfonate,

[0594] 3 3-dimethyl-2-oxobutyl diethylsulfonium camphor sulfonate,

[0595] 2-cyclohexyl-2-oxoethyl diethylsulfonium camphor sulfonate,

[0596] 2-cyclopentyl-2-oxoethyl diethylsulfonium camphor sulfonate,

[0597] dibutyl-(2-oxopropyl)sulfonium camphor sulfonate,

[0598] dibutyl-(2-oxobutyl)sulfonium camphor sulfonate,

[0599] dibutyl-(2-oxopentyl)sulfonium camphor sulfonate,

[0600] dibutyl-(2-oxohexyl)sulfonium camphor sulfonate,

[0601] dibutyl-(2-oxoheptyl)sulfonium camphor sulfonate,

[0602] dibutyl-(2-oxooctyl)sulfonium camphor sulfonate,

[0603] dibutyl-(3-methyl-2-oxobutyl)sulfonium camphor sulfonate,

[0604] dibutyl-(3,3-dimethyl-2-oxobutyl) sulfonium camphor sulfonate,

[0605] dibutyl-( 2-cyclohexyl-2-oxoethyl) sulfonium camphor sulfonate,

[0606] dibutyl-(²-cyclopentyl-2-oxoethyl) sulfonium camphor sulfonate,

[0607] diisopropyl-(2-oxopropyl)sulfonium camphor sulfonate,

[0608] diisopropyl-(2-oxobutyl)sulfonium camphor sulfonate,

[0609] diisopropyl-(2-oxopentyl)sulfonium camphor sulfonate,

[0610] diisopropyl-(2-oxohexyl)sulfonium camphor sulfonate,

[0611] diisopropyl-(2-oxoheptyl)sulfonium camphor sulfonate,

[0612] diisopropyl-(2-oxooctyl)sulfonium camphor sulfonate,

[0613] diisopropyl-(3-methyl-2-oxobutyl)sulfonium camphor sulfonate,

[0614] 3,3-dimethyl-2-oxobutyl diisopropylsulfonium camphor sulfonate,

[0615] 2-cyclohexyl-2-oxoethyl diisopropylsulfonium camphor sulfonate,

[0616] 2-cyclopentyl-2-oxoethyl diisopropylsulfonium camphor sulfonate,

[0617] tert-butyl methyl(2-oxopropyl)sulfonium camphor sulfonate,

[0618] tert-butyl methyl(2-oxobutyl)suifonium camphor sulfonate,

[0619] tert-butyl methyl(2-oxopentyl)sulfonium camphor sulfonate,

[0620] tert-butyl methyl(2-oxohexyl)sulfonium camphor sulfonate,

[0621] tert-butyl methyl(2-oxoheptyl)sulfonium camphor sulfonate,

[0622] tert-butyl methyl(2-oxooctyl)sulfonium camphor sulfonate,

[0623] tert-butyl methyl(3-methyl-2-oxobutyl)sulfonium camphorsulfonate,

[0624] tert-butyl (3,3-dimethyl-2-oxobutyl) methylsulfonium camphorsulfonate,

[0625] tert-butyl (2-cyclohexyl-2-oxoethyl) methylsulfonium camphorsulfonate,

[0626] tert-butyl (2-cyclopentyl-2-oxoethyl) methylsulfonium camphorsulfonate,

[0627] cyclohexyl methyl(2-oxopropyl)sulfonium camphor sulfonate,

[0628] cyclohexyl methyl(2-oxobutyl)sulfonium camphor sulfonate,

[0629] cyclohexyl methyl(2-oxopentyl)sulfonium camphor sulfonate,

[0630] cyclohexyl methyl(2-oxohexyl)sulfonium camphor sulfonate,

[0631] cyclohexyl methyl(2-oxoheptyl)sulfonium camphor sulfonate,

[0632] cyclohexyl methyl(2-oxooctyl)sulfonium camphor sulfonate,

[0633] cyclohexyl methyl(3-methyl-2-oxobutyl)sulfonium camphorsulfonate,

[0634] cyclohexyl (3,3-dimethyl-2-oxobutyl) methylsulfonium camphorsulfonate,

[0635] cyclohexyl (2-cyclohexyl-2-oxoethyl) methylsulfonium camphorsulfonate,

[0636] cyclohexyl (2-cyclopentyl-2-oxoethyl) methylsulfonium camphorsulfonate,

[0637] 2-oxopropyl thiacyclopentanium camphor sulfonate,

[0638] 2-oxobutyl thiaoyclopentanium camphor sulfonate,

[0639] 2-oxopentyl thiacyclopentanium camphor sulfonate

[0640] 2-oxohexyl thiacyclopentanium camphor sulfonate,

[0641] 2-oxoheptyl thiacyclopentanium camphor sulfonate,

[0642] 2-oxooctyl thiacyclopentanium camphor sulfonate,

[0643] 3-methyl-2-oxobutyl thiacyclopentanium camphor sulfonate,

[0644] 3,3-dimethyl-2-oxobutyl thiacyclopentanium camphor sulfonate,

[0645] 2-cyclohexyl-2-oxoethyl thiacyclopentanium camphor sulfonate,

[0646] 2-cyclopentyl-2-oxoethyl thiacyclopentanium camphor sulfonate,

[0647] 2-oxopropyl thiacyclohexanium camphor sulfonate,

[0648] 2-oxobutyl thiacyclohexanium camphor sulfonate,

[0649] 2-oxopentyl thiacyclohexanium camphor sulfonate,

[0650] 2-oxohexyl thiacyclohexanium camphor sulfonate,

[0651] 2-oxoheptyl thiacyclohexanium camphor sulfonate,

[0652] 2-oxooctyl thiacyclohexanium camphor sulfonate,

[0653] 3-methyl-2-oxobutyl thiacyclohexanium camphor sulfonate,

[0654] 3,3-dimethyl-2-oxobutyl thiacyclohexanium camphor sulfonate,

[0655] 2-cyclohexyl-2-oxoethyl thiacyclohexanium camphor sulfonate,

[0656] 2-cyclopentyl-2-oxoethyl thiacyclohexanium camphor sulfonate,

[0657] 2-oxopropyl (1,4-thioxanium) camphor sulfonate,

[0658] 2-oxobutyl (1,4-thioxanium) camphor sulfonate,

[0659] 2-oxopentyl (1,4-thioxanium) camphor sulfonate,

[0660] 2-oxohexyl (1,4-thioxanium) camphor sulfonate,

[0661] 2-oxoheptyl (1,4-thioxanium) camphor sulfonate,

[0662] 2-oxooctyl (1,4-thioxanium) camphor sulfonate,

[0663] 3-methyl-2oxobutyl ( 1,4-thioxanium) camphor sulfonate,

[0664] 3,3-dimethyl-2-oxobutyl (1,4-thioxanium) camphor sulfonate,

[0665] 2-cyolohexyl-2-oxoethyl (1, 4-thioxanium) camphor sulfonate,

[0666] 2-cyclopentyl-2-oxoethyl (1,4-thioxanium) camphor sulfonate,

[0667] 2-oxopropyl (4-oxothiacyclohexanium) camphor sulfonate,

[0668] 2-oxobutyl (4-oxothiacyclohexanium) camphor sulfonate,

[0669] 2-oxopentyl (4-oxothiacyclohexanium) camphor sulfonate.

[0670] 2-oxohexyl (4-oxothiacyclohexanium) camphor sulfonate,

[0671] 2-oxoheptyl (4-oxothiacyclohexanium) camphor sulfonate,

[0672] 2-oxooctyl (4-oxothiacyclohexanium) camphor sulfonate,

[0673] 3-moetyl-2-oxobutyl (4-oxothiacyclohexanium) camphor sulfonate,

[0674] 3,3-dimethyl-2-oxobutyl (4-oxothiacyclohexanium) camphorsulfonate,

[0675] 2-cyclohexyl-2-oxoethyl (4-oxothiacyclohexanium) camphorsulfonate,

[0676] 2-cyclopentyl-2-oxoethyl (4-oxothiacyclohexanium) camphorsulfonate,

[0677] 2-oxopropyl (1,4-dithianium) camphor sulfonate,

[0678] 2-oxobutyl (1,4-dithianium) camphor sulfonate,

[0679] 2-oxopentyl (1, 4-dithianium) camphor sulfonate,

[0680] 2-oxohexyl (1,4-dithianium) camphor sulfonate,

[0681] 2-oxoheptyl (1,4-dithianium) camphor sulfonate,

[0682] 2-oxooctyl (1,4-dithianium) camphor sulfonate,

[0683] 3-methyl-2-oxobutyl (1,4-dithianium) camphor sulfonate

[0684] 3,3-dimethyl-2-oxobutyl (1,4-dithianium) camphor sulfonate,

[0685] 2-cyclohexyl-2-oxoethyl (1,4-dithianium) camphor sulfonate,

[0686] 2-cyclopentyl-2-oxoethyl (1, 4-dithianium) camphor sulfonate, and

[0687] 2-oxocyclohexyl thiacyclopentanium camphor sulfonate,

[0688] By the addition the sulfonium salt represented by the formula(I), the line edge roughness can be improved. With a resist compositionusing the sulfonium salt represented by the formula (I) singly as anacid generator, it becomes difficult to obtain sufficient sensitivityand resolution. Then, in the resist composition of the presentinvention, at least one onium salt selected from the formulae (IIa) and(IIb) is used in combination with such a sulfonium salt of the formula(I) as an acid generator By using such an onium salt-based acidgenerator in combination therewith, it is possible to improve thesensitivity and the resolution as compared with the case where thesulfonium salt-based acid generator of the formula (I) is used singly,and it is possible to improve the line edge roughness as compared withthe case where at least one onium salt-based acid generator selectedfrom the formulae (IIa) and (IIb) is used singly.

[0689] In the formulae (IIa) and (IIb) each respectively representingtriphenylsulfonium salt and diphenyliodonium salt, P¹, P², P³, P⁴, andP⁵ each independently represent hydrogen, a hydroxyl group, an alkylgroup having from 1 to 6 carbon atoms, or an alkoxy group having from 1to 6 carbon atoms. The alkyl group and the alkoxy group may be straightchain or branched when they each have 3or more carbon atoms. Specificexamples of an alkyl group include methyl group, ethyl group, propylgroup, isopropyl group, butyl group, tert-butyl group, pentyl group, andhexyl group. Examples of the alkoxy group include methoxy group, ethoxygroup, propoxy group, and butoxy group. Whereas, in the formulae (IIa)and (IIb), P⁶SO₃ ⁻ and P⁷SO₃ ⁻ each forming an anion represent anorganosulfonate ion. P⁶ and P⁷ each may be an organic group having aboutfrom 1 to 12 carbon atoms. Examples thereof include a perfluoroalkylgroup having from 1 to a carbon atoms, an alkyl group having from 1 to acarbon atoms, an aromatic group having from 6 to 12 carbon atoms and acamphor group. Specific examples of the perfluoroalkyl group having from1 to 8 carbon atoms, the alkyl group having from 1 to 8 carbon atoms,and the aromatic group having from 6 to 12 carbon atoms include the sameones as described above.

[0690] If there is a commercially available product of thetriphenylsulfonium salt represented by the formula (IIa) or thediphenyliodonium salt represented by the formula (IIb), it may be usedas it is. Alternatively, it may be produced in accordance with theconventional method. The triphenylsulfonium salt (IIa) maybe produced bythe following methods, for example:

[0691] a method in which the corresponding triphenylsulfonium bromide isallowed to react with a silver salt of the sulfonic acid having the sameanion as the anion of the objective compound; a method In which thecorresponding diphenylsulfoxide, a benzene compound, and aperfluoroalkanesulfonic acid are allowed to mutually react in thepresence of a trifluoroacetic acid anhydride in accordance with thedescription in “Chem. Pharm. Bull.”, Vol29, 3753 (1981);

[0692] a method in which the corresponding aryl Grignard reagent isallowed to react with thionyl chloride, and then the reaction product isallowed to react with triorganosilyl halide to prepare atriarylsulfonium halide, which is then allowed to react with the silversalt of the sulfonic acid having the same anion as the anion of theobjective compound in accordance with the description in JP-A-8-311018;and the like. Whereas, the compound of the formula (IIa) wherein P¹, P²,and/or P³ is a hydroxyl group can be produced by treating thetriphenylsulfonium salt having a tert-butoxy group on the benzene ringwith the sulfonic acid having the same anion as the anion of thecompound, and eliminating the tert-butoxy group therefrom in accordancewith the description in JP-A-8-311018.

[0693] Whereas, the diphenyliodonium salt (IIb) can be produced with thefollowing methods, for example;

[0694] a method in which an lodyl sulfuric acid and the correspondingaryl compound are allowed to react, followed by the addition of thesulfonic acid having the same anion as the anion of the objectivecompound in accordance with the description in “J. Am. Chem. Soc.”,vol.81, 342 (1959);

[0695] a method in which iodine and a trifluoroacetic acid are added ina mixed solution of an acetic acid anhydride and a fuming nitric acid toobtain a reaction product, which is then reacted with the correspondingaryl compound, followed by the addition of a sulfonic acid having thesame anion as the anion of the objective compound;

[0696] a method in which to a mixture of the corresponding arylcompound, an acetic anhydride, and potassium iodate, is added dropwise aconcentrated sulfuric acid, followed by the addition of the sulfonicacid having the same anion as the anion of the objective compound inaccordance with the description in JP-A-9-179302.

[0697] Examples of the triphenylsulfonium salt represented by theformula (IIa) and diphenyliodonium salt represented by the formula (IIb)include:

[0698] triphenylsulfonium methanesulfonate,

[0699] triphenylsulfonium ethanesulfonate,

[0700] triphenylsulfonium butanesulfonate,

[0701] triphenylsulfonium perfluorobutanesulfonate,

[0702] triphenylsulfonium p-toluenesulfonate,

[0703] triphenylsulfonium camphor sulfonate,

[0704] 4-methylphenyldiphenylsulfonium methanesulfonate,

[0705] 4-methylphenyldiphenylsulfonium ethanesulfonate,

[0706] 4-methylphenyldiphenylsulfonium butanesulfonate,

[0707] 4-methylphenyldiphenylsulfonium benzensulfonate,

[0708] 4-methylphenyldiphenylsulfonium p-toluenesulfonate,

[0709] 4-methylphenyldiphenylsulfonium camphor sulfonate,

[0710] 4-methylphenyldipheaylsulfonium perfluorobutanesulfonate,

[0711] 4-hydroxyphenyldiphenylsulfonium perfluorobutanesulfonate,

[0712] 4-methylphenyldiphenylsulfonium perfluorobutanesulfonate,

[0713] tris (4-methylphenyl) sulfonium perfluorobutanesulfonate,

[0714] tris (4-methoxyphenyl) sulfonium perfluorobutanesulfonate,

[0715] 4-methylphenyldiphenylsulfonium perfluorooctanesulfonate,

[0716] 4-hydroxyphenyldiphenylsulfonium perfluorooctanesulfonate,

[0717] 4-methylphenyldiphenylsulfonium perfluorooctanesulfonate,

[0718] tris(4-methylphenyl)sulfonium perfluorooctanesulfonate,

[0719] tris(4-methoxyphenyl)sulfonium perfluorooctanesulfonate,

[0720] diphenyl iodonium perfluorobutanesulfonate,

[0721] di(4-methoxyphenyl) todonium perfluorooctanesulfonate,

[0722] di(4-tert-butyliphenyl) iodonium perfluorooctanesulfonate,

[0723] di(4-tert-butyliphenyl) iodonium methanesulfonate,

[0724] di(4-tert-butyliphenyl) todonium ethanesulfonate,

[0725] di(4-tert-butyliphenyl) iodonium butanesulfonate,

[0726] di(4-tert-butyliphenyl) iodonium benzensulfonate,

[0727] di(4-tert-butyliphenyl) todonium p-toluenesulfonate, and

[0728] di(4-tert-butyliphenyl) iodonium camphor sulfonate.

[0729] Then, the resin component constituting the resist composition ofthe present invention will be described. The resin has a polymerizationunit having a group instable against an acid. The resin for a chemicallyamplifying type positive resist itself is generally alkali-insoluble, oralkali-slightly soluble. However, a part of the groups are cleaved bythe action of the acid, and the resin becomes alkali-soluble aftercleavage. The groups instable against an acid in the present inventionmay also be such various ones known in the art. As the groups instableagainst an acid, specifically, various esters of a carboxylic acid canbe exemplified. Example of the esters of carboxylic acid include alkylesters such as methyl ester and tert-butyl ester, acetal type esterssuch as methoxymethyl ester, ethoxymethyl ester, 1-ethoxyethyl ester,1-isobutoxyethyl ester, 1-isopropoxyethyl ester, 1-ethoxypropyl ester,1-(2-methoxyethoxy)ethyl ester, 1-(2-acetoxyethoxy)ethyl ester,1-[2-(1-adamantyloxy)ethoxy]ethyl ester,1-[2-(1-adamantanecarbonyloxy)ethoxy]ethyl ester,tetrahydro-2-furylester, and tetrahydro-2-pyranylester, and alicyclicesters such as isobornyl ester, 2-alkyl-2-adamantly ester, and1-(1-adamantyl)-1-alkylalkyl ester. Monomers leading to polymerizationunits having such carboxylic acid esters may be the ones of(meth)acrylate type such as methacrylic acid ester and acrylic acidester, or the one in which a carboxylic acid ester group is bonded to analicyclic monomer, such as norbornenecarboxylic acid ester,tricyclodecenecarboxylic acid ester, or tetracyclodecenecarboxylic acidester.

[0730] Among such monomers, the monomers having a bulky group includingan alicyclic one such as 2-alkyl-2-adamantyl or1-(1-adamantyl)-1-alkylalkyl as the group which is cleaved by the actionof an acid is preferably used because of the excellent resolution.Examples of such monomers containing a bulky group include (meth)acrylicacid-2-alkyl-2-adamantyl, (meth)acrylic acid1-(l-adamantyl)-1-alkylalkyl,

[0731] 5-norbonene-2-carboxylic acid 2-alkyl-2-adamantyl, and

[0732] 5-norbonene-2-carboxylic acid

[0733] 1-(1-adamantyl)-1-alkylalkyl. Among them, (meth)acrylicacid-2-alkyl-2-adamantyl Is preferably used as the monomer because ofthe excellent resolution. Typical examples of such(meth)acrylic-2-alkyl-acid 2-adamantyl include acrylic

[0734] acid-a-methyl-a-adamantyl, methacrylic

[0735] acid-2-methyl-2-adamantyl, acrylic

[0736] acid2-ethyl-2-adamantyl, methacrylic

[0737] acid-2-ethyl-2-adamantyl, and acrylic

[0738] acid-2-n-butyl-2-adamantyl. Among them, (meth)acrylic

[0739] acid-2-ethyl-2-adamantyl is particularly preferably used becauseof the good balance between the sensitivity and the heat resistance. Ifrequired, other monomers having a group which is cleaved by the actionof an acid may also be used in combination.

[0740] (Meth)acrylic acid 2-alkyl-2-adamantyl can be generally producedby the reaction between 2-alkyl-adamantanol or a metal salt thereof, andan acrylic acid halide or a methacrylic acid halide.

[0741] The resin specified in the present invention may further contain,in addition to the polymerization unit having a group instable againstan acid as described above, another polymerization unit which is notcleaved, or is less likely to be cleaved by the action of an acid.Examples of the other polymerization unit which can be contained thereininclude a polymerization unit having a free carboxylic acid group suchas an acrylic acid or a methacrylic acid, a polymerization unit of analiphatic unsaturated dicarboxylic acid anhydride such as a maleic acidanhydride or an itaconic acid anhydride, a polymerization unit of2-norbonene, a polymerization unit of (meth)acrylonitrile, andpolymerization units of various (meth)acrylic acid esters. Thepolymerization unit of hydroxystyrene is not preferred for ArF exposurebecause the amount of light absorption is large, but it is preferablyused for KrF exposure because there occurs no problem of lightabsorption.

[0742] Particularly, it is preferable in terms of the adhesion of theresist to a substrate that at least one polymerization units selectedfrom a polymerization unit of p-hydroxystyrene; a polymerization unit ofm-hydroxystyrene; a polymerization unit of (meth)acrylio acid3-hydroxy-1-adamantyl; a polymerization unit a of (meth)acrylic acid3,5-hydroxy-1-adamantyl; a polymerization unit of(meth)acryloyloxy-γ-butyrolactone in which the lactone ring may besubstituted by alkyl; polymerization units of alicyclic lactones eachrepresented by the following formulae (IIIa) and (IIIb):

[0743] wherein R¹ and R² each independently represent hydrogen ormethyl, and n represents a number of from 1 to 3; and the like iscopolymerized.

[0744] The (meth)acrylic acid 3-hydroxy-1-adamantyl, (meth)acrylic acid3,5-dihydroxy-1-adamantyl are commercially available. Alternatively,they can also be produced by, for example, reacting the correspondinghydroxy adamant an with a (meth)acrylic acid or a halide thereofWhereas, the (meth)acryloyloxy-γ-butyrolactone can be produced byreacting α-, or β-bromo-γ-butyrolactone in which the lactone ring may besubstituted by alkyl with an acrylic acid or a methacrylic acid, orreacting α-, or β-hydroxy-γ-butyrolactone in which the lactone ring maybe substituted by alkyl with an acrylic acid halide or a methacrylicacid halide. As the monomers leading to the polymerization units ofalicyclic lactones each represented by the formula (IIIa) and (IIb), forexample, (meth)acrylic acid ester sofalicyclic lactones having ahydroxyl group, mixtures thereof, such as those shown below, and thelike can be mentioned. These esters can be produced, for example, by thereaction between the corresponding alicyclic lactone having a hydroxylgroup and (meth)acrylic acids (ex., JP-A-2000-26446).

[0745] Any of the polymerization units of (meth)acrylic acid3-hydroxy-1-adamantyl, and the polymerization units of (meth)acrylicacid 3,5-dihydroxy-1-adamantyl, the polymerization units ofα-(meth)acryloyloxy-γ-butyrolactone and the polymerization units ofβ-(meth)acryloyloxy-γ-butyrolactone, and the polymerization units ofalicyclic lactones represented by the formulae (IIIa) or (IIIb) has ahigh polarity. The presence of any of them in a resin improves theadhesion of a resist containing it to a substrate. These polymerizationunits also contributes to the improvement of the resolution of theresist.

[0746] Examples of the monomers leading to the polymerization units of(meth)acryloyloxy-γ-butyrolactone include α-acryloyloxy-γ-butyrolactone,α-methacryloyloxy-γ-butyrolactone,α-acryloyloxy-β,β-dimethyl-γ-butyrolactone,α-methacryloyloxy-β,β-dimethyl-γ-butyrolactone,α-acryloyloxy-α-methyl-γ-butyrolactone,α-methacryloyloxy-α-methyl-β-butyrolactone,β-acryloyloxy-γ-butyrolactone, β-methacryloyloxy-γ-butyrolactone, andβ-methacryloyloxy-α-methyl-γ-butyrolactone.

[0747] For KrF excimer laser exposure, even if the polymerization unitof hydroxystyrene is used as the polymerization unit of a resin,sufficient transmittance can be obtained. Specifically, p-, orm-hydroxystylene copolymer resins as shown below can be mentioned assuch resins. Each of such copolymer resins can be obtained by radicalpolyrerizing the corresponding (meth)acrylic acid ester monomers,acetoxystyrene, and styrene, followed by deacetylation by an acid.

[0748] In these cases, use of 2-alkyl-2-adamantyl or1-adamantyl-1-alkylalkyl as the group instable against an acid is moreadvantageous in terms of the dry etching resistance.

[0749] Further, the resin containing the polymerization unit of2-norbonene has a strong structure because it has an alicyclic groupdirectly on its main chain, and hence it exhibits an excellent dryetching resistance characteristic. The polymerization unit of2-norbonene can be introduced into the main chain by radicalpolymerization using a corresponding 2-norbonene and an aliphaticunsaturated dicarboxylic acid anhydrides such as maleic acid anhydrideand itaconic acid anhydride in combination. Therefore, thepolymerization unit of 2-norbornene is formed by cleavage of its doublebond, and may be represented by the formula (IV). Further, thepolymerization unit of a maleic acid anhydride and the polymerizationunit of an itaconic acid anhydride, which are the polymerization unitsof aliphatic unsaturated dicarboxylic acid anhydrides, are formed bycleavage of their respective double bonds, and may be represented by theformulae (V) and (VI), respectively.

[0750] In the formula (IV), R³ and R⁴ each independently representhydrogen, alkyl having from 1 to 3 carbon atoms, hydroxyalkyl havingfrom 1 to 3 carbon atoms, carboxyl, cyano, or —COOZ (z is an alcoholresidue ) group, or R³ and R⁴ may both together form a carboxylic acidanhydride residue represented by —C(═O)OC(═O)—. When R³ and/or R⁴ isalkyl, specific examples thereof include methyl, ethyl, and propyl.Specific examples of hydroxyalkyl as R³ or R⁴ include hydroxymethyl and2-hydroxyethyl. When R³and/or R⁴ is a —COOZ group, it is formed byesterifying carboxyl. As the alcohol residues corresponding to Z, forexample, alkyl having about from 1 to 8 carbon atoms which may besubstituted, 2-osooxolan-3-, or -4-yl, and the like can be mentioned.Herein, as the substituents for the alkyl, a hydroxyl group, alicyclichydrocarbon residues, and the like can be exemplified. Then, when R³and/or R⁴ is a carboxylic acid ester residue represented by —COOZ,specific examples thereof Include methoxycarbonyl, ethoxycarbonyl,2-hydroxyethoxycarbonyl, tert-butyloxycarbonyl,2-osooxolan-3-yloxycarbonyl,

[0751] 2-oxooxolan-4-yloxycarbonyl,

[0752] 1,1,2-trimethylpropoxycarbonyl,

[0753] 1-cyclohexyl-l-methylethoxycarbonyl,

[0754] 1-(4-methylcyclohexyl)-l-methylethoxycarbonyl, and

[0755] 1-(1-adamantyl)-1-methylethoxycarbonyl.

[0756] Examples of the monomers for deriving 2-norbornene represented bythe formula (IV) include:

[0757] 2-norbornene,

[0758] 2-hydroxy-5-norbornene,

[0759] 5-norbornene-2-carboxylic acid,

[0760] 5-norbornene-2-methylcarboxylate,

[0761] 5-norbornene-2-t-butylcarboxylate.

[0762] 5-norbornene-2-(1-cyclohexyl-1-methylethyl)carboxylate,

[0763] 5-norbornene-2-[1-(4-methylcyclohexyl)-1-methylethyl]carboxylate,

[0764]5-norbornene-2-[1-(4-hydroxycyclohexyl)-1-methylethyyl]carboxylate,

[0765] 5-norbornene-2-[l-methyl-1-(4-oxocyclohexyl)-ethyl]carboxylate,

[0766] 5-norbornene-2-[1-(l-adamantyl)-1-methylethyl]carboxylate,

[0767] 5-norbornene-2-(1-methylcyclohexyl) carboxylate,

[0768] 5-norbornene-2-(2-methyl-2-adamantyl)carboxylate,

[0769] 5-norbornene-2-(2-ethyl-2-adamantyl)carboxylate,

[0770] 5-norbornene-2-(2-hydroxy-1-ethyl)carboxylate,

[0771] 5-norbornene-2-methanol, and

[0772] 5-norbornene-2, 3-dicarboxylic acid anhydride.

[0773] It is preferable that the resin to be used in the presentinvention generally contains the polymerization unit having a groupinstable against an acid in an amount in the range of from 10 to 80 mol% although the amount varies according to the kind of radiation forpatterning exposure, the kind of the group Instable against an acid,etc. When the polymerization unit of (meth)acrylicacid2-alkyl-2adamantyl or (meth)acrylic acid1-(1-adamantyl)-1-alkylalkyl is used as the group instable against anacid, it is advantageous that this unit is contained in an amount of notless than is mol % based on the total amount of the resin. Further, whenin addition to the polymerization unit instable against an acid, otherpolymerization units which are less likely to be cleaved by the actionof an acid, such as the polymerization units of (meth)acrylic acid3-hydroxy-1-adamantyl, the polymerization units of (meth)acrylic acid3,5-hydroxy-1-adamantyl and α-methacryloyloxy-γ-butyrolactone, thepolymerization unit of β-methacryloyloxy-γ-butyrolactone, thepolymerization units of alicyclic lactones represented by the formulae(IIIa) or (IIIb), the polymerization unit of hydroxystyrene, thepolymerization unit of 2-norbornene represented by the formula (IV), thepolymerization unit of maleic acid anhydride represented by the formula(V) and the polymerization unit of itaconic acid anhydride representedby the formula (VI), are present therein, the total amount thereof ispreferably in the range of from 20 to 90 mol % based on the total amountof the resin.

[0774] When 2-norbornes and aliphatic unsaturated dicarboxylic acidanhydrides are used as copolymerization monomers, since they tend to bedifficult to polymerize, thy are preferably used in excess amounts inconsideration of this point.

[0775] It is also known that, generally in a chemical amplifying typepositive resist composition, performance deterioration due to thedeactivation of an acid associated with leaving after exposure can bereduced by adding basic compounds, especially basic nitrogen-containingorganic compounds such as amines as quenchers. It is also preferable inthe present invention that such basic compounds are added. Concreteexamples of the basic compounds to be used as quenchers include the onesrepresented by the following formulae:

[0776] wherein R¹¹ and R¹² , which are same or different from eachother, represent hydrogen, or cycloalkyl, aryl or alkyl which may beoptionally substituted with a hydroxyl; R¹³, R¹⁴ and R¹⁵, which are sameor different from each other, represent hydrogen or cycloalkyl, aryl oralkyl which may be optionally substituted with a hydroxyl; R¹⁶represents cycloalkyl or alkyl which may be optionally substituted witha hydroxyl: and A represents alkylene, carbonyl, imino.) The alkylrepresented by R¹¹ to R¹⁷ and alxoxy represented by R¹³ to R¹⁵ may haveabout 1 to 6 carbon atoms. The cycloalkyl represented by R¹¹ to R¹⁶ mayhave about 5 to 10 carbon atoms and the aryl represented by R¹¹ to R¹⁵may have about 6 to 10 carbon atoms. The alkylene represented by A mayhave about 1 to 6 carbon atoms and may be straight-chained or branched.

[0777] The resist composition of the present invention preferablycontains the resin in an amount in the range of 80 to 99.9% by weight,and the acid generator in an amount in the range of 0.1 to 20% by weightbased on the total solid component weight of the resist composition. Inthe resist composition of the present invention, the amounts ratio ofthe sulfonium salt represented by the formula (I) to the onium saltselected from the triphenylsulfonium salt represented by the formula(IIa) and diphenyliodonium salt represented by the formula (IIb) isusually in the range of about 9:1 to 1:9 by weight, preferably 8:2 to2:8, by weight.

[0778] When a basic compound is used as a quencher, it Is preferablycontained in an amount in the range of 0.01 to 1% by weight based on thetotal solid component weight of the resist composition. The compositionmay also contain, if required, small amount of various additives such assensitizers, dissolution inhibitors, other resins, surfactants,stabilizers, and dyes so far as the objects of the present invention isnot harmed.

[0779] The resist composition of the present invention generally becomesa resist solution in the state in which the above-described componentsare dissolved in a solvent to be applied on a substrate such as asilicon wafer by an usual method such as spin coating. The solventherein used may be one which dissolves each component, has anappropriate drying rate, and provides a uniform and smooth coating afterevaporation of the solvent, and can be one which is generally used inthis field. Examples thereof include glycol ether esters such asethylcellosolve acetate, methylcellosolve acetate, and propyleneglycolmonomethyl ether acetate; esters such as ethyl lactate, butylacetate, amyl acetate, and ethyl pyruvate; ketones such as acetone,methyl isobutyl ketone, 2-heptanone, and cyclohexanone; and cyclicesters such as γ-butyrolactone. These solvents can be used alone or incombination of two or more thereof.

[0780] The resist film applied on a substrate, and dried is subjected toan exposure treatment for patterning. Then, after a heat-treatment forpromoting a protecting deblocking reaction, development by an alkalideveloper is conducted. The alkali developer herein used can be variouskinds of alkaline aqueous solutions used in this field. In general, anaqueous solution of tetramethylammoniumhydroxide or (2-hydroxyethyl)trimethylammoniumhydroxide (so-called collide) is often used.

[0781] The present invention will be described in more detail by way ofexamples, which should not be construed as limiting the scope of thepresent invention. All parts In examples are by weight unless otherwisestated. The weight-average molecular weight is a value determined fromgel permeation chromatography using polystyrene as a reference standard.

ACID GENERATOR SYNTHESIS EXAMPLE 1

[0782] synthesis of acid generator B1

[0783] (1) Into a four-necked flask, where charged 70.17 parts oftetrahydrothiophene and 750 parts of acetone, to which 150 parts of1-bromopinacolone was added dropwise, followed by stirring at roomtemperature for 24 hours. The precipitated crystal was collected byfiltration, and washed with 100 parts of tert-butylmethyl ether, anddried to obtain 161.3 parts of 3,3-dimethyl-2-oxobutylthiacyclopentanium bromide.

[0784] (2) Into a four-necked flask, were charged 80 parts of the3,3-dimethyl-2-oxobutyl thiacyclopentanium bromide obtained in the step(1), and 3200 parts of acetonitrile, to which 56.33 parts of potassiumtrifluoromethanesulfonate was added dropwise, followed by stirring atroom temperature for 18 hours. The precipitated potassium bromide wascollected by filtration, and the filtrate was concentrated. Acetone wasadded thereto, followed by stirring at room temperature for 16 hours,and the insoluble matters were collected by filtration. The filtrate wasfurther concentrated, and acetone was added thereto. Then, the mixturewas charged in tert-butylmethyl ether, thereby to obtain 94.73 parts ofthe objective substance. This compound was found to be3,3-dimethyl-2-oxobutyl thiacyclopentanium trifluoromethanesulfonaterepresented by the following formula by ¹H—NMR (“GX-270” manufactured byNippon Denshi):

[0785]¹H—NMR (chloroform-d, internal standard substancetetramethylsilane): δ (ppm)

[0786] 1.24 (s, 9H); 2.26-2.33 (m, 2H); 2.42-2.52 (m, 2H); 3.45-3.55 (m,2H); 3.61-3.71 (m, 2H); 4.96 (s, 2H).

ACID GENERATOR SYNTHESIS EXAMPLES 1-2

[0787] synthesis of acid generator B1

[0788] (1) According to the same procedure as in Acid GeneratorSynthesis Example 1 (1), except for increasing the reaction size, 3,3-dimethyl-2-oxobutyl thiacyclopentanium bromide was obtained.

[0789] (2) into a four necked flask, were charged 169.58 parts of the3,3-dimethyl-2-oxobutyl thiacyclopentanium bromide obtained in the step(1), and 3391.59 parts of acetonitrile, and the resulting mixture wascooled to 5° C. Thereto, 100 parts of trifluoromethanesulfonio acid wasadded dropwise, followed by stirring at 5° C. for 1.5 hours. Thereafter,the reaction mass was concentrated to 270 parts, to which 680 parts ofethyl actate was added. To the resulting mixtures 300 parts oftert-butylmethyl ether was added by stirring, and the precipitatedmatters were collected by filtration. The filter cake thus obtained wasdissolved in 500 parts of ethyl actate, and, then, concentrated to 420parts. Thereto, 50 parts of tert-butylmethyl other was added bystirring, the precipitated matters were collected by filtration, and theprecipitated matter was dried to obtain 156,22 parts of the objectivesubstance.

ACID GENERATOR SYNTHESIS EXAMPLES 1-2

[0790] synthesis of acid generators B2 and B3

[0791] Experiments were carried out in the same manner as in the step(2) of Acid Generator Synthesis Example 1, except that potassiumperfluorobutanesulfonate and potassium perfluorooctanesulfonate wereused in place of the potassium trifluoromethanesulfonate in the step (2)of Acid Generator Synthesis Example 1. thereby to obtain3,3-dimethyl-2-oxobutyl thiacyclopentanium perfluorobutanesulfonate and3,3-dimethyl-2-oxobutyl thiacyclopentanium perfluorooctanesulfonate,respectively.

[0792]¹H—NMR (dimethyl sulfoxide-d6, internal standard substancetetramethylsilane) of 3,3-dimethyl-2-oxobutyl thiacyclopentaniumperfluorobutanesulfonate): δ (ppm)

[0793] 1.15 (s, 9H), 2.13-2.23 (m, 4H); 3.33-3.38 (m, 2H), 3.47-3.54 (m,2H); 4.85 (s, 2H).

[0794]¹H—NMR (chloroform-d, internal standard substancetetramethylsilane) of 3,3-dimethyl-2-oxobutyl thiacyclopentaniumperfluorooctanesulfonate): δ (ppm)

[0795] 1.25 (s, 9H); 2.24-2.32 (m, 2H); 2.49-2.56 (m, 2H); 3.56-3.69 (m,4H); 5.05 (s, 2H).

ACID GENERATOR SYNTHESIS EXAMPLE 4

[0796] synthesis of acid generator

[0797] Into a four-necked flask, were charged 2.3 parts of3,3-dimethyl-2-oxobutyl thiacyclopentanium bromide and 912 parts ofacetonitrile, to which a solution obtained by dissolving 2.4 parts ofsilver p-toluenesulfonate in 7.2 parts of acetonitrile was addeddropwise, followed by stirring at room temperature for 22 hours. Theprecipitated silver bromide was collected by filtration, and washed with30 parts of acetonitrile. A mixture of the filtrate and the wash liquidwas concentrated to 3.3 parts. Thirty parts of acetonitrile was addedthereto, followed by stirring at room temperature for 2 hours, and theinsoluble matters were collected by filtration. The filtrate wasconcentrated to2.75 parts. The concentrated residue was recrystallizedfrom a mixed solvent of ethyl acetate and tert-butylmethyl ether,thereby to obtain 0.68 parts of the objective substance. This compoundwas found to be 3,3-dimethyl-2-oxobutyl thiacyclopentaniump-toluenesulfonate by ¹H—NMR (“GX-270” manufactured by Nippon Denshi):

[0798]¹H—NMR (dimethyl sulfoxide-d6, internal standard substancetetramethylsilane); δ (ppm)

[0799] 1.12 (s, 9H); 2.05-2.29 (m, 4H); 2.29 (s, 3H); 3.32-3.56 (m, 4H);4.89 (s, 2H); 7.12 (d, 2H): 7.48 (d,2H).

ACID GENERATOR SYNTHESIS EXAMPLE 5

[0800] synthesis of acid generator B5

[0801] Into a four-necked flask, were charged 2.3 parts of3,3dimethyl-2-oxobutyl thiacyclopentanium bromide and 92 parts ofacetonitrile, to which a solution obtained by dissolving 2.9 parts ofsilver camphorsulfonate in 8.6 parts of acetonitrile was added dropwise,followed by stirring at room temperature for 18 hours. The precipitatedsilver bromide was collected by filtration, and washed with 30 parts ofacetonitrile. A mixture of the filtrate and the wash liquid wasconcentrated to 3.2 parts. Ten parts of acetonitrile was added thereto,followed by stirring at room temperature for 2 hours, and the insolublematters were collected by filtration. The filtrate was concentrated to2.92 parts. The concentrated residue was recrystallized from a mixedsolvent of ethyl acetate and tert-butylmethyl ether, thereby to obtain2.46 parts of the objective substance. This compound was found to be3,3-dimethyl-2-oxobutyl thiacyclopentanium camphorsulfonate by ¹H—NMR(“GX-270” manufactured by Nippon Denshi):

[0802]¹H—NMR (dimethyl sulfoxide-d6, internal standard substancetetramethylsilane): δ (ppm)

[0803] 0.74 (s, 31); 1.05 (s, 3H): 1.15 (s, 9H); 1.20-1.39 (m, 2H);1.76-1.95 (m, 3H); 2.10-2,28 (m, 5H); 2.36 (d, 1H); 2.66-2.74 (m, 1H);2.86 (d, 1H):3.33-3.58 (m, 4H); 4.90 (s,2H)

RESIN SYNTHESIS EXAMPLE 1

[0804] (Resin A1)

[0805] 2-ethyl-2-adamantyl methacrylate, 3-hydroxy-l-adamantylmethacrylate and α-methacryloyloxy-γ-butyrolactone were charged at amolar ratio of 5:2.5:2.5 (20,0 parts 9.5 parts: 7.3 parts) Thereto,methylisobutyl ketone, the amount thereof being two times by weightbased on the whole monomers, was added to form a monomer solution. Then,was added azobisisobutyronitrile as an initiator in an amount of 2 mol %based on the whole monomer. Then, the mixture was heated at 80° C. forabout 8 hours. After cooling the reaction mass, it was poured into alarge amount of heptane to cause precipitation. This precipitationoperation was repeated three times to purify the resin. A copolymerhaving a molecular weight of about 9,200 was obtained. This is calledResin A1.

RESIN SYNTHESIS EXAMPLE 2

[0806] (Resin A2)

[0807] 2-ethyl-2-adamantyl methacrylate, 3-hydroxy-1-adamantyl acrylate,norbornene and maleic anhydride were charged at a molar ratio of 2:2:3:3(10.0 parts: 9.0 parts: 5.7 parts: 5.9 parts). Thereto, methylisobutylketone, the amount thereof being two times by weight based on the wholemonomers, was added to form a monomer solution, and the resultingmixture was heated up to 80° C. under nitrogen atmosphere. Then, wasadded azobisisobutyronitrile as an initiator in an amount of 3 mol %based on the whole monomer. Under nitrogen atmosphere, and the resultingmixture was heated at 80° C. for about 15 hours. Thereafter, thereaction mass was poured into a large amount of methanol to causeprecipitation. This precipitation operation was repeated three times topurify the resin. A copolymer having a molecular weight of about 12160and a molecular weight dispersion of 1.90 was obtained(17.1 parts). Thisis called Resin A2.

RESIN SYNTHESIS EXAMPLE 3

[0808] (Resin A3)

[0809] 2-ethyl-2-adamantyl methacrylate,5-methacryloyloxy-2,6-norbornanelactone andα-methacryloyloxy-γ-butyrolactone were charged at a molar ratio of 2;1:1(11.1 g:5.0 g, 3.8 g), and 50 g of 1.4-dioxane was added to this to givea solution. Thereto was added 0.30 g of azobisisobutyronitrile as aninitiator, then, the mixture was heated up to 85° C. and stirred for 5hours. Then, the reaction mass was poured into a large amount ofn-heptane to cause precipitation. This precipitation operation wasrepeated three times to purify there in, obtaining a copolymer having amolecular weight of about 9100 and a molecular weight dispersion of1.72. This is called Resin A3.

RESIN SYNTHESIS EXAMPLE 4

[0810] (Resin A4)

[0811] Into a four-necked flask, were charged 10.5 g (42 mmol) ofacrylic acid 1-(1-adamantyl) -1-methylethyl, 9. 4 g (42 mmol) of acrylicacid 3-hydroxy-1-adamantyl, 6.0 g (63 mmol) of 2-norbornene, and 6.2 g(63 mmol) of maleic acid anhydride, and the mixture was dissolved in64.2 g of methylisobutyl ketone. Nitrogen was blown therein for bubblingfor 30 minutes, and then the temperature was raised up to 80° C. Intothe solution, was added dropwise a solution obtained by dissolving 1.0 g(6-3 mmol) of 2,2′-azobis(isobutyronitrile) in 16.0 g of methylisobutylketone, and the temperature was kept at 80° C. for 15 hours. Theresulting reaction mass was cooled, and charged in 1134 g of methanol.As a result, a white crystal was precipitated, and the crystal wascollected by filtration. The crystal was washed with methanol, and driedunder reduced pressure at 30° C. for 15 hours. The crystal of copolymerof acrylic acid I-adamantyl-1-methylethyl, acrylic acid3-hydroxy-l-adamantyl, 2-norbornene, and maleic acid anhydride thusobtained was present in an amount of 16.4 g, and had a molecular weightof 6900 in terms of polystyrene. This is referred to as resin A4.

RESIN SYNTHESIS EXAMPLE 5

[0812] (Resin A5)

[0813] (1) Into a flask, were charged 16.4 g (0.07 mol) of methacrylic20 acid-2-methyl-2-adamantyl, 45.4 g (0.28 mol) of p-aoetoxystyrene, and123.6 g of isopropanol. After nitrogen replacement, the temperature wasraised up to 75° C. Into the solution, was added dropwise a solutionobtained by dissolving 4.84 g (0.021 mol) ofdimethyl2,2-azobis(2-methylpropionate) in 9.7 g of isopropanol. Thesolution was aged at 75° C. for about 0.5 hour, and under reflux forabout 11 hours, and then diluted with acetone. The resulting solutionwas charged in heptane to effect crystallization, and the crystal wascollected by filtration. The crystal obtained was dried. The crystal ofCopolymer of methacrylic acid-2-methyl-2-adamantyl and p-acetoxystyreneobtained was present in an amount of 54.2 g.

[0814] (2) Into a flask, were charged 53.0 g (0.30 mol in terms ofmonomer unit) of the copolymer of methacrylic acid-2-methyl-2-adamantyland p-acetoxystyrene (20:80) obtained above, 5.3 g (0,043 mol) of4-dimethylaminopyridine, and 159.0 g of methanol, followed by agingunder reflux for 20 hours. After cooling, the mixture was neutralizedwith 3.13 g (0.052 mol) of a glacial acetic acid, and the mixture wascharged in water to effect crystallization. Then, the crystal wascollected by filtration. Thereafter, the crystal was dissolved inacetone, and the solution was charged in water to effectcrystallization. Then, the crystal was collected by filtration. A seriesof the operations were repeated three times, and then the crystalobtained was dried. The crystal of the copolymer of methacrylicacid-2-methyl-2-adamantyl and p-hydroxystyrene obtained was present inan amount of 37.8 g. It had a weight-average molecular weight of about7900, and a molecular weight dispersion of 1.72 (GPC method: in terms ofpolystyrene). The copolymerization ratio was determined to be about20:80 by a nuclear magnetic resonance (¹³C—NMR) spectrometer. This resinis referred to as resin A5.

[0815] Resin A6:

[0816] 4-hydroxystyrene/styrene/acrylic acid t-butyl (60/20/20)copolymer weight-average molecular weight, 11000 (TSM4, manufactured byMaruzen Oil, Co. Ltd.)

[0817] Resist compositions were prepared using the acid generators B1 toB3, C1 and C2, and evaluations of the resist compositions wereconducted.

[0818] Acid generators

[0819] Acid generator B3: 3,3-dimethyl-2-oxobutyl thiacyclopentaniumtrifluoromethane sulfonate,

[0820] Acid generator B2: 3,3-dimethyl-2-oxobutyl thiacyclopentaniumperfluorobutane sulfonate

[0821] Acid generator B3: 3,3-dimethyl-2-oxobutyl thiacyclopentaniumperfluorooctane sulfonate

[0822] Acid generator B4: 3,3-dimethyl-2-oxobutyl thiacyclopentaniump-toluene sulfonate

[0823] Acid generator B5: 3,3-dimethyl2-oxobutyl thiacyclopentaniumcamphor sulfonate

[0824] Acid generator C1: 4-methylphenyldiphenylsulfoniumperfluorooctanesulfonate,

[0825] Acid generator C2: di(4-tert-butylphenyl) iodonium camphorsulfonate.

EXAMPLES 1-6 AND COMPARATIVE EXAMPLES 1-4

[0826] Resin shown in Table 1, acid generators shown in Table 1 and thecomponents listed below were mixed and dissolved. The resultant solutionwas filtered through a fluorine resin filter having a pore diameter of0.2 μm to give a resist solution Resin (Kind thereof is shown inTable 1) 10 parts Acid generator 57 parts (Amount and kind thereof areshown In Table 1) Quencher: 2,6-diisopropylaniline (Amount thereof islisted in Table 1) Solvent: propyleneglycol monomethylether acetateγ-butyrolactone  3 parts

[0827] A silicon wafer was coated with a composition “DUV-30J”(manufactured by Brewer Co. Ltd.) and baked under conditions of 215° C.for 60 seconds so that an organic reflection-preventing membrane havinga thickness of 1,600 angstrom was formed on the wafer. On the siliconwafer thus prepared, the resist solution obtained above was applied byspin-coat or so that the film thickness after drying was 0.335 μm. Afterapplying the resist solution, the wafer was pre-baked on a direct hotplate at a temperature shown in Table 1, column “PB”, for 60 seconds.

[0828] The wafer having a resist film formed thereon was irradiated withan ArF excimer stepper [“NSR-ArF”, manufactured by Nikon, NA=0.55,σ=0.6] through a line-and-space pattern, changing the exposure amountstepwise. The exposed wafer was subjected to post-exposure baking (PEB)on a hot plate at a temperature shown in Table 1, column “PEB”, for 60seconds. Then the wafer was subjected to paddle development with 2.38%by weight aqueous tetramethyl ammonium hydroxide solution for 60seconds.

[0829] The developed pattern formed on a substrate was observed by ascanning electron microscope and assessed for the effective sensitivityand the resolution by the following methods:

[0830] Effective sensitivity: This is expressed in the minimum amount ofexposure which gave 1:1 line-and-space pattern of 0.18 μm.

[0831] Resolution this is expressed in the minimum size which gaveline-and-space pattern spitted at the exposure amount of the effectivesensitivity.

[0832] Line edge roughness (Smoothness of pattern wall) Wall of thespitted line pattern was observed by a scanning electron microscope.

[0833] ◯: The smoothness of the wall is better than those in Comparativeexamples.

[0834] ×: The smoothness of the wall is almost same as those inComparative examples.

[0835] Percent transmission: On a quartz glass wafer, the resistsolution obtained above was applied so that the film thickness afterprebaking was 0.335 μm. Then, the wafer was pre-baked according to thesame conditions as above to form a resist film. Percent transmission ofthe resist film at 193 nm was measured by a spectrophotometer. Theresults are shown in Table 2. TABLE 1 Acid generator Quencher P B P E BNo. Resin (part) (part) (° C.) (° C.) Example 1 A1 B1 (0.5) + 0.015 110115 C1 (0.2) Example 2 A1 B2 (0.5) + 0.015 110 115 C1 (0.2) Example 3 A1B3 (0.5) + 0.015 110 125 C1 (0.2) Example 4 A2 B3 (0.5) + 0.015 110 125C1 (0.2) Example 5 A3 B3 (0.5) + 0.015 100 125 C1 (0.2) Example 6 A4 B1(0.25) + 0.008 110 125 C1 (0.2) Comparative A1 C1 (0.2) 0.015 110 125Example 1 Comparative A2 C1 (0.2) 0.015 110 125 Example 2 Comparative A3C1 (0.2) 0.015 100 125 Example 3 Comparative A4 C1 (0.2) 0.015 100 125Example 4

[0836] TABLE 2 Effective sensitivity Resolution Percent Line edge No.mJ/cm² μm transmission roughness Example 1 48 0.16 68 ∘ Example 2 570.15 58 ∘ Example 3 41 0.16 67 ∘ Example 4 41 0.16 67 ∘ Example 5 700.16 68 ∘ Example 6 29 0.16 65 ∘ Comparative 53 0.15 64 — Example 1Comparative 76 0.16 64 — Example 2 Comparative 88 0.16 65 — Example 3Comparative 44 0.16 67 — Example 4

[0837] As shown in Table 2, the resist compositions of Examples arebetter in line edge roughness (smoothness of pattern wall) than those ofComparative example. They impart good sensitivity and resolution withoutlowering Percent transmission.

EXAMPLES 7-12 AND COMPARATIVE EXAMPLES 5 AND 6

[0838] Resin shown in Table 3, acid generators shown in Table 3 and thecomponents listed below were mixed and dissolved The resultant solutionwas filtered through a fluorine resin filter having a pore diameter of0.2 μm to give a resist solution. Resin (Kind thereof is shown in Table3) 13.5 parts Acid generator (Amount and kind thereof are shown in Table3) Quencher: triisopropanotamine 0.07 parts Solvent: ethyllactate   60parts

[0839] A silicon wafer was coated with a composition “DUV-30J”(manufactured by Brewer Co. Ltd.) and baked under conditions of215° C.for 60 seconds so that an organic reflection-preventing membrane havinga thickness shown in Table 3 was formed on the wafer. On the siliconwafer thus prepared, the resist solution obtained above was applied byspin-coator so that the film thickness after drying was 0.49 μm. Afterapplying the resist solution, the wafer was pre-baked on a directhotplate at a temperature shown in Table 3, column “PB”, for 60 seconds.

[0840] The wafer having a resist film formed thereon was irradiated withan KrF excimer stepper [“NSR-2205EX12B”, manufactured by Nikon, NA=0.55,⅔ annular illumination] through a line-and-space pattern, changing theexposure amount stepwise. The exposed wafer was subjected topost-exposure baking (FEB) on a hot plate at a temperature shown inTable 3, column “PEB”, for60 seconds. Then the wafer was subjected topaddle development with 2.38% by weight aqueous tetramethyl ammoniumhydroxide solution for 60 seconds.

[0841] The developed pattern formed on a substrate was observed by ascanning electron microscope and assessed for the effective sensitivityand the resolution by the following methods:

[0842] Effective sensitivity; This is expressed in the minimum amount ofexposure which gave 1:1 line-and-space pattern of 0.20 μm.

[0843] Resolution: This is expressed in the minimum size which gaveline-and-space pattern spitted at the exposure amount of the effectivesensitivity.

[0844] Line edge roughness (Smoothness of pattern wall) Wall of thespitted line pattern was observed by a scanning electron microscope.

[0845] ◯: The smoothness of the wall is better than those in Comparativeexamples.

[0846] ×: The smoothness of the wall is almost same as those inComparative examples.

[0847] Percent transmission; On a quartz glass wafer, the resistsolution obtained above was applied so that the film thickness afterprebaking was 0.49 μm. Then, the safer was pre-baked according to thesame conditions as above to form a resist film. Percent transmission ofthe resist film at 248 nm was measured by a spectrophotometer. Theresults are shown in Table 4. TABLE 3 ** Acid generator P B P E B No. ÅResin (part) (° C.) (° C.) Example 7 1600 A5 B2 (0.35) + 120 140 C2(0.7) Example 8 1600 A6 B1 (0.35) + 130 140 C2 (0.35) Example 9 1600 A6B2 (0.35) + 130 140 C2 (0.35) Example 10 1600 A6 B3 (0.35) + 130 140 C2(0.35) Example 11  600 A6 B4 (0.35) + 130 140 C2 (0.35) Example 12  600A6 B5 (0.35) + 130 140 C2 (0.35) Comparative 1600 A5 C2 (0.7) 120 140Example 5 Comparative 1600 A6 C2 (0.35) 130 140 Example 6

[0848] TABLE 4 Effective sensitivity Resolution Percent Line edge No.mJ/cm² μm transmission roughness Example 7 50 0.16 72 ∘ Example 8 780.16 76 ∘ Example 9 82 0.16 76 ∘ Example 10 90 0.16 76 ∘ Example 11 820.16 75 ∘ Example 12 96 0.16 75 ∘ Comparative 48 0.16 72 — Example 5Comparative 120  0.19 77 — Example 6

[0849] As shown in Table 4, the resist compositions of Examples arebetter in line edge roughness (smoothness of pattern wall) than those ofComparative example, They impart good sensitivity and resolution withoutlowering Percent transmission.

[0850] The chemical amplifying type positive resist composition of thepresent invention provides a resist pattern having an exceedinglyimproved line edge roughness, and it is also excellent in various resistperformances such as dry etching resistance, sensitivity, andresolution. Therefore, this composition is suitable for lithographyusing a KrF excimer laser, or an ArE excimer laser, whereby ahigh-performance resist pattern can be provided.

What is claimed is:
 1. A chemical amplifying type positive resistcomposition which comprises: (A) an acid generator containing (a) asulfonium salt represented by the following formula (I):

wherein Q¹ and Q² each independently represent a straight chain orbranched alkyl group having from 1 to 6 carbon atoms or a cycloalkylgroup having from 3 to 10 carbon atoms, or Q¹ and Q² form, together witha sulfur atom to which Q¹ and Q² are adjacent, an heteroalicyclic groupwhich may further contain an oxygen atom and a sulfur atom Q³ representsa hydrogen atom, Q⁴represents a straight chain or branched alkyl grouphaving from 1 to 6 carbon atoms or a cycloalkyl group having from 3 to10 carbon atoms, or Q³ and Q4 form, together with a CHC(O) group towhich Q³ and Q4 are adjacent, a 2-oxocycloalkyl group; and Q⁵SO₃ ⁻represents an organosulfonate ion, provided that when Q⁵ represents aperfluoroalkyl group having from 1 to 8 carbon atoms, there is excludedthe case where Q¹ represents a straight chain or branched alkyl grouphaving from 1 to 6 carbon atoms, Q² represents a straight chain orbranched alkyl group having from 1 to 6 carbon atoms, or a cycloalkylgroup having from 3 to 10 carbon atoms, and Q³ and Q⁴ represent,together with their adjacent CHC(O) group, a 2-oxocycloalkyl group, and(b) at least one onium salt selected from a triphenylsulfonium saltrepresented by the following formula (IIa), and a diphenyliodonium saltrepresented by the following formula (IIb):

wherein P¹ to P⁵ each Independently represent hydrogen, a hydroxylgroup, an alkyl group having from 1 to 6 carbon atoms, or an alkoxygroup having from 1 to 6 carbon atoms; and P⁶SO₃ ⁻ and P⁷SO₃ ⁻ eachindependently represent an organosulfonate ion; and (B) a resin whichhas a polymerization unit having a group instable against an acid, andis alkali-insoluble or -slightly soluble itself, but is converted toalkali-soluble by the action of an acid.
 2. The chemical amplifying typepositive resist composition according to claim 1 wherein Q¹ and Q² form,together with a sulfur atom to which Q¹ and Q² are adjacent, anheteroalicyclic group.
 3. The chemical amplifying type positive resistcomposition according to claim 1 wherein Q⁵, P⁶ and P⁷ eachindependently are a perfluoroalkyl group having from 1 to 8 carbonatoms, an alkyl group having from 1 to a carbon atoms, an aromatic grouphaving from 6 to 12 carbon atoms or a camphor group.
 4. The chemicalamplifying type positive resist composition according to claim 1 whereinthe amounts ratio of the sulfonium salt represented by the formula (I)to the onium salt selected from the triphenylsulfonium salt representedby the formula (IIa) and diphenyliodonium salt represented by theformula (IIb) is in the range of about 9:1 to 1:9 by weight.
 5. Thechemical amplifying type positive resist composition according to claim1 wherein (B)the resin contains the polymerization unit having a groupinstable against an acid in an amount in the range of from 10 to 80 mol%.
 6. The chemical amplifying type positive resist composition accordingto claim 1 wherein the polymerization unit having a group instableagainst an acid is polymerization unit of (meth)acrylic acid2-alkyl-2-adamantyl or (meth)acrylic acid 1-adamantyl-1-alkylalkyl. 7.The chemical amplifying type positive resist composition according toclaim 1 wherein (B)the resin further contains at least onepolymerization units selected from a polymerization unit ofp-hydroxystyrene; a polymerization unit of m-hydroxystyrene; apolymerization unit of (meth)acrylic acid 3-hydroxy-1-adamantyl; apolymerization unit of (meth)acrylic acid 3,5-hydroxy-1-adamantyl; apolymerization unit of (meth)acryloyloxy-γ-butyrolactone in which thelactone ring may be substituted by alkyl; polymerization units ofalicyclic lactones each represented by the following formulae (IIIa) and(IIIb):

wherein R¹ and R² each independently represent hydrogen or methyl, and nrepresents a number of from 1 to
 3. 8. The chemical amplifying typepositive resist composition according to claim 7 wherein (B)the resinfurther contains a polymerization unit of 2-norbornene and apolymerization unit of an aliphatic unsaturated dicarboxylic acidanhydrides.
 9. The chemical amplifying type positive resist compositionaccording to claim 1 which further comprises an amine as quencher.
 10. Asulfonium salt represented by the following formula (Ia):

wherein Q⁶ represents a perfluoroalkyl group having from 1 to 8 carbonatoms, an alkyl group having from 1 to 8 carbon atoms, an aromatic grouphaving from 6 to 12 carbon atoms or a camphor group; when Q⁶ representsa perfluoroalkyl group having from 1 to a carbon atoms, Q¹ and Q² eachindependently represent a straight chain or branched alkyl group havingfrom 1 to 6 carbon atoms or a cycloalkyl group having from 3 to 10carbon atoms, or Q¹ and Q² form, together with a sulfur atom to which Q¹and Q²are adjacent, an heteroalicyclic group which may further containan oxygen atom and a sulfur atom, represents a hydrogen atom, 4represents a straight chain or branched alkyl group having from 1 to 6carbon atoms or a cycloalkyl group having from 3 to 10 carbon atoms;when Q⁶ represents an alkyl group having from 1 to 8 carbon atoms, anaromatic group having from 6 to 12 carbon atoms or a camphor group, Q¹and Q² each independently represent a straight chain or branched alkylgroup having from 1 to 6 carbon atoms or a cycloalkyl group having from3 to 10 carbon atoms, or Q¹ and Q² form, together with a sulfur atom towhich Q¹ and Q² are adjacent, an heteroalicyclic group which may furthercontain an oxygen atom and a sulfur atom, Q³ represents a hydrogen atom,and Q⁴ represents a straight chain or branched alkyl group having from 1to 6 carbon atoms or a cycloalkyl group having from 3 to 10 carbonatoms, or Q³ and Q4 form, together with their adjacent CHC(O) group, a2-oxocycloalkyl group.